Method for manufacturing semiconductor device

ABSTRACT

An object is to provide a method for manufacturing a semiconductor device which suppresses an influence on a semiconductor element due to entry of an impurity element, moisture, or the like from outside even in the case of thinning or removing a substrate after forming a semiconductor element over the substrate. A feature is to form an insulating film functioning as a protective film on at least one side of the substrate by performing surface treatment on the substrate, to form a semiconductor element such as a thin film transistor over the insulating film, and to thin the substrate. As the surface treatment, addition of an impurity element or plasma treatment is performed on the substrate. As a means for thinning the substrate, the substrate can be partially removed by performing grinding treatment, polishing treatment, or the like on the other side of the substrate.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing asemiconductor device, and particularly to a method for manufacturing aflexible semiconductor device which can be bent.

2. Description of the Related Art

In recent years, a semiconductor element provided over a rigid substratesuch as a glass substrate has been actively developed for use in adisplay and a photoelectric conversion element such as an LCD, anorganic EL display, a photo sensor, and a solar cell. On the other hand,as for an element using a Si wafer, an IC chip has been miniaturized andthinned for use in a cellular phone and the like. In addition, asemiconductor device which transmits and receives data without contact(also referred to as an RFID (Radio Frequency Identification) tag, an IDtag, an IC tag, an IC chip, an RF (Radio Frequency) tag, a wireless tag,an electronic tag, or a wireless chip) has been actively developed. Inany case of using a rigid substrate such as a glass substrate, a Sisubstrate, or the like for manufacturing such a semiconductor device, areduction in thickness of a substrate is required along with needs forminiaturization and thinning.

In addition, recently, a flexible device has been required for an RFIDtag embedded in paper, a display which can be wound around a pen, aprofile sensor for a three-dimensional shape or a color sensor, a handroll PC, clothes of which design is changed by changing the color, orthe like. Therefore, a reduction in thickness holds an important key.

In the case of forming a semiconductor element using a pre-thinnedsubstrate to manufacture a thin semiconductor device, warpage of thesubstrate due to stress, difficulty in handling, and misalignment inlithography, a printing step, and the like become problems.Consequently, a method for thinning a substrate after forming asemiconductor element over the substrate is generally used.

As for a reduction in substrate thickness by grinding or polishing,conventionally, a thinner film is formed while improving substrateplanarity using an abrasive grain as a polishing step after thinning asubstrate using a grindstone as a grinding step. An abrasive grainhaving lower \Tickers hardness than that of a substrate to be polishedtends to be used as a device for improving planarity. For example,cerium oxide (CeO₂) for a glass substrate, silicon oxide (SiO₂) for asilicon wafer, or the like, which has lower Vickers hardness than thatof the substrate, makes it possible to selectively polish only a portionin close contact with an object by chemical reaction (for example, seeReference 1: Japanese Patent Laid-Open No. 2004-282050).

In addition, there is a technique for removing a glass substrate by wetetching using chemical reaction (for example, see Reference 2: JapanesePatent Laid-Open No. 2002-87844).

However, when a substrate is thinned or removed after providing asemiconductor element over the substrate, it is concerned that animpurity element, moisture, or the like from outside easily enters thesemiconductor element and adversely affects the semiconductor element.

SUMMARY OF THE INVENTION

In view of the aforementioned problems, it is an object of the presentinvention to provide a method for manufacturing a semiconductor devicewhich suppresses an influence on a semiconductor element due to entry ofan impurity element, moisture, or the like from outside even in the caseof thinning or removing a substrate after providing a semiconductorelement over the substrate.

One feature of a method for manufacturing a semiconductor device of thepresent invention is to include the steps of forming an insulating filmfunctioning as a protective film on at least one side of the substrateby performing surface treatment on the substrate, forming asemiconductor element such as a thin film transistor over the insulatingfilm, and thinning the substrate. Note that an insulating film may beformed on the other side of the substrate. As the surface treatment,addition of an impurity element or plasma treatment is performed on thesubstrate. As a means for thinning the substrate, the substrate can bepartially removed by performing grinding treatment, polishing treatment,or the like on the other side of the substrate. In addition, theinsulating film formed on the one side of the substrate may be exposedby removing the substrate. The substrate can be removed by performingeither or both grinding treatment and polishing treatment, or acombination of etching by chemical treatment with either or bothgrinding treatment and polishing treatment.

Another feature of a method for manufacturing a semiconductor device ofthe present invention is to include the steps of forming a nitridedlayer by performing plasma treatment on a substrate in a nitrogenatmosphere to nitride one side of the substrate, forming a thin filmtransistor over the nitrided layer, and thinning the substrate byperforming either or both grinding treatment and polishing treatment onthe other side of the substrate. In addition, an insulating film formedon the one side of the substrate may be exposed by removing thesubstrate. In addition, the nitrided layer formed on the one side of thesubstrate may be exposed by removing the substrate. The substrate can beremoved by performing either or both grinding treatment and polishingtreatment, or a combination of etching by chemical treatment with eitheror both grinding treatment and polishing treatment. Note that thenitrided layer in the present invention contains at least nitride, andnitride is formed on the substrate by nitriding the surface of thesubstrate. In addition, there may be the case where the nitride formedon the substrate exists so as to have a concentration distributiondepending on conditions of surface treatment.

Still another feature of a method for manufacturing a semiconductordevice of the present invention is to include the steps of forming athin film transistor over one side of a substrate, thinning thesubstrate by performing either or both grinding treatment and polishingtreatment on the other side of the substrate, and forming a nitridedlayer by performing plasma treatment on the thinned substrate in anitrogen atmosphere to nitride a surface of the thinned substrate.

Yet another feature of a method for manufacturing a semiconductor deviceof the present invention is to include the steps of forming firstnitride by performing plasma treatment on a substrate in a nitrogenatmosphere to nitride one side of the substrate, forming a thin filmtransistor over the first nitride, thinning the substrate, and formingsecond nitride by performing plasma treatment on the thinned substratein a nitrogen atmosphere to nitride a surface of the thinned substrate.The substrate is thinned by performing either or both grinding treatmentand polishing treatment on the other side of the substrate. In addition,etching using chemical treatment may be performed in combination withgrinding treatment or polishing treatment.

According to the above feature of the invention, sealing can beperformed with a flexible film to cover a semiconductor element such asthe thin film transistor after thinning or removing the substrate.

In addition, a feature of the method for manufacturing a semiconductordevice of the present invention according to the above feature, theplasma treatment is performed using a high frequency wave under theconditions that an electron density is in the range of 1×10¹¹ cm⁻³ to1×10¹³ cm⁻³ and an electron temperature is in the range of 0.5 eV to 1.5eV.

One feature of a semiconductor device of the present invention is toinclude a nitrided layer formed on a surface of a substrate, and a thinfilm transistor provided over the nitrided layer, in which a thicknessof the substrate is in the range of 1 μm to 100 μm, and at least part ofthe nitrided layer contains a noble gas element.

Another feature of a semiconductor device of the present invention is toinclude a nitrided layer formed on a surface of a substrate, and a thinfilm transistor provided over the nitrided layer, in which a thicknessof the substrate is 1 μm or less, and at least part of the nitridedlayer contains a noble gas element.

Still another feature of a semiconductor device of the present inventionis to include a thin film transistor provided over one side of asubstrate, a nitrided layer formed on the other side of the substrate,in which a thickness of the substrate is in the range of 1 μm to 100 μm,and at least part of the nitrided layer contains a noble gas element.

Yet another feature of a semiconductor device of the present inventionis to include a first nitrided layer formed on one side of a substrate,a second nitrided layer formed on the other side of the substrate, and athin film transistor provided over the first nitrided layer, in which athickness of the substrate is in the range of 1 μm to 100 μm, and atleast part of the first nitrided layer and the second nitrided layercontains a noble gas element.

Even in the case of manufacturing a flexible semiconductor device bythinning or removing a substrate after providing a semiconductor elementsuch as a transistor over the substrate, an impurity element, moisture,or the like entering the semiconductor element from outside can besuppressed and prevented from adversely affecting characteristics of thesemiconductor device, by providing a protective film over the substrateby performing surface treatment before thinning or removing thesubstrate or after thinning the substrate. Further, even in the case ofperforming surface treatment on the substrate provided with thesemiconductor element, damage to the semiconductor element can bereduced by performing high-density plasma treatment as the surfacetreatment.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1E are diagrams showing an example of a method formanufacturing a semiconductor device of the present invention.

FIGS. 2A to 2E are diagrams showing an example of a method formanufacturing a semiconductor device of the present invention.

FIGS. 3A to 3E are diagrams showing an example of a method formanufacturing a semiconductor device of the present invention.

FIGS. 4A to 4C are diagrams showing an example of a method formanufacturing the semiconductor device of the present invention.

FIGS. 5A to 5D are diagrams showing an example of a method formanufacturing a semiconductor device of the present invention.

FIGS. 6A and 6B are diagrams showing examples of a semiconductor devicesof the present invention.

FIGS. 7A to 7C are diagrams showing examples of semiconductor devices ofthe present invention.

FIGS. 8A to 8D are diagrams showing examples of types of usage of asemiconductor device of the present invention.

FIGS. 9A to 9C are diagrams showing an example of a method formanufacturing a semiconductor device of the present invention.

FIGS. 10A and 10B are diagrams showing an example of a method formanufacturing the semiconductor device of the present invention.

FIGS. 11A and 11B are diagrams showing an example of a method formanufacturing the semiconductor device of the present invention.

FIGS. 12A and 12B are diagrams showing an example of a method formanufacturing the semiconductor device of the present invention.

FIG. 13A is a diagram of a semiconductor device of the presentinvention, and FIGS. 13B and 13C are diagrams showing examples of typesof usage of a semiconductor device of the present invention.

FIGS. 14A to 14H are diagrams showing examples of types of usage of asemiconductor device of the present invention.

FIGS. 15A and 15B are diagrams showing an example of a semiconductordevice of the present invention.

FIG. 16 is a diagram showing an example of a semiconductor device of thepresent invention.

FIGS. 17A to 17G are diagrams showing examples of types of usage of asemiconductor device of the present invention.

FIGS. 18A to 18F are diagrams showing examples of types of usage of asemiconductor device of the present invention.

FIGS. 19A and 19B are diagrams showing an example of an apparatus formanufacturing a semiconductor device of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment modes of the present invention are hereinafter explained withreference to the drawings. However, the present invention is not limitedto the following description. As is easily known to a person skilled inthe art, the mode and the detail of the invention can be variouslychanged without departing from the spirit and the scope of the presentinvention. Thus, the present invention is not interpreted as beinglimited to the following description of the embodiment modes. Note thatthe same reference numeral is commonly used to denote the same componentamong different drawings in the structure of the present inventionexplained below.

The present invention manufactures a flexible semiconductor device,after forming a semiconductor element such as a thin film transistor(TFT) over a rigid substrate, by thinning or removing the substrate byperforming any or all of grinding treatment, polishing treatment,etching by chemical treatment, and the like on the substrate. Further,the present invention includes a mode in which a protective film isformed by performing surface treatment such as plasma treatment on thesubstrate before thinning or removing the substrate or after thinningthe substrate. Even in the case of thinning or removing the substrate,entry of an impurity element, moisture, or the like into thesemiconductor element provided over the substrate can be suppressed byforming the protective film.

Hereinafter, examples of methods for manufacturing semiconductor devicesof the present invention are explained with reference to FIGS. 1A to 2E.Note that FIGS. 1A to 1E show the case of performing surface treatmenton a substrate in advance before thinning or removing the substrate, andFIGS. 2A to 2E show the case of performing surface treatment on athinned substrate after thinning the substrate.

Initially, the case of performing surface treatment on a substratebefore thinning or removing the substrate is explained with reference toFIGS. 1A to 1E.

First, a substrate 101 is prepared, and its surface is washed usinghydrofluoric acid (HF), or alkaline or pure water (FIG. 1A).

As the substrate 101, a glass substrate of barium borosilicate glass,aluminoborosilicate glass, or the like, a quartz substrate, a ceramicsubstrate, a metal substrate including stainless steel, or the like maybe used. Alternatively, a semiconductor substrate of Si or the like maybe used.

Next, surface treatment is performed on one side of the substrate 101(FIG. 1B). The surface treatment on the substrate 101 is performed byplasma treatment or doping with an impurity element. For example, anitrided layer 102 (hereinafter also referred to as an insulating film102) is formed by performing plasma treatment on a surface of thesubstrate 100 in a nitrogen atmosphere to nitride the surface of thesubstrate 101. In this case, the insulating film 102 contains at leastnitride, and there may be the case where the nitride formed on thesubstrate has a concentration distribution (here, a concentrationdistribution of nitrogen) depending on conditions of the surfacetreatment. Alternatively, an oxidized layer may be formed by oxidizingthe surface of the substrate 100 by performing plasma treatment in anoxygen atmosphere, or an oxynitrided layer may be formed by performingplasma treatment in an atmosphere containing oxygen and nitrogen tooxynitride the surface of the substrate 101. Furthermore, the nitridedlayer 102 can be formed by adding nitrogen (N) atoms to the surface ofthe substrate 101 by doping, or the nitrided layer 102 can be formed byperforming heat treatment in a nitrogen atmosphere. Note that thenitrided layer 102 may be formed not only on the surface of thesubstrate 101 but on the other side depending on an apparatus used forthe plasma treatment or the like or conditions thereof.

Note that the plasma treatment in the present invention includesoxidizing treatment, nitriding treatment, oxynitriding treatment,hydrogenating treatment, surface modification treatment, and the like onan object to be treated such as a semiconductor film, an insulatingfilm, or a conductive film, and a gas used for the treatment may beselected depending on the purpose. For example, in the case ofperforming nitriding treatment on an object to be treated (here, thesubstrate 101), plasma treatment is performed in an atmospherecontaining nitrogen (for example, in an atmosphere containing nitrogen(N₂) and a noble gas (including at least one of He, Ne, Ar, Kr, and Xe),an atmosphere containing nitrogen, hydrogen, and a noble gas, anatmosphere containing NH₃ and a noble gas, an atmosphere containing NO₂and a noble gas, or an atmosphere containing N₂O and a noble gas). Inthe case of performing oxidizing treatment on the object to be treated,plasma treatment is performed in an atmosphere containing oxygen (forexample, in an atmosphere containing oxygen (O₂) or dinitrogen monoxide,and a noble gas (including at least one of He, Ne, Ar, Kr, and Xe), anatmosphere containing oxygen or dinitrogen monoxide, hydrogen (H₂), anda noble gas). Note that the treated object (here, the insulating film102 formed on the surface of the substrate 101) may contain a noble gasused for plasma treatment. For example, in the case of using Ar, thetreated object may contain Ar.

As the plasma treatment, plasma treatment using a high frequency wave(such as a microwave) under the conditions of high density (preferably,in the range of 1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³) and low electron temperature(preferably, in the range of 0.5 eV to 1.5 eV) is preferably performed(the plasma treatment is hereinafter referred to as high-density plasmatreatment). By performing plasma excitation by introducing a highfrequency wave such as a microwave, high-density plasma can be generatedat low electron temperature, and the surface of the object to be treatedcan be oxidised or nitrided with an oxygen radical (which may contain anOH radical) or a nitrogen radical (which may contain an NH radical) thatis generated by the high-density plasma. Thus, by performinghigh-density plasma treatment on an object to be treated, damage byplasma to the object to be treated can be suppressed since plasmadensity is high and electron temperature in the vicinity of the objectto be treated is low. In addition, because of high plasma density, thenitrided layer or oxidized layer formed by performing nitridingtreatment or oxidizing treatment on the object to be treated with theuse of plasma treatment is superior in uniformity of thickness or thelike to a film formed by a CVD method, a sputtering method, or the like,and a dense film can be formed. In addition, because of low plasmaelectron temperature, the nitriding treatment or the oxidizing treatmentcan be performed at lower temperature as compared to conventional plasmatreatment or thermal oxidation method. Therefore, for example, in thecase of using a glass substrate as the substrate, the nitridingtreatment or oxidizing treatment can be performed sufficiently even inthe case of performing the plasma treatment at a temperature lower by100° C. or more than a strain point of the glass substrate.

Next, an element group 103 including a semiconductor element such as atransistor or a diode is formed over the insulating film 102 formed onthe surface of the substrate 101 (FIG. 1C).

The element group 103 is formed with a semiconductor element including,for example, a transistor, a diode, a solar cell, or the like. As thetransistor, a thin film transistor (TFT) using a semiconductor filmformed over a rigid substrate such as a glass substrate as a channel, afield effect transistor (FET) formed using a semiconductor substrate ofSi or the like, which uses the substrate as a channel, an organic TFTusing an organic material as a channel, or the like can be provided. Asthe diode, various diodes such as a variable capacitance diode, aSchottky diode, and a tunnel diode can be applied. In the presentinvention, all types of integrated circuits such as a CPU, a memory, anda microprocessor can be provided using the transistor, diode, or thelike. In addition, the element group 103 can take the form of includingan antenna in addition to the semiconductor element such as atransistor. A semiconductor device of which element group 103 isprovided with an antenna operates using an AC voltage generated in theantenna, and can transmit and receive data to/from an external device(reader/writer) without contact by modulating an AC voltage applied tothe antenna. Note that the antenna may be formed together with anintegrated circuit including a transistor or may be electricallyconnected after being formed separately from the integrated circuit.

Next, the other side of the substrate 101 (a side opposite to the sideprovided with the insulating film 102) is subjected to grindingtreatment, polishing treatment, or etching by chemical treatment,thereby thinning or removing the substrate 101 (FIG. 1D). In thegrinding treatment, a surface of an object to be treated (here, thesubstrate 101) is grinded and smoothed using grains of an abrasivestone. In the polishing treatment, the surface of the object to betreated is smoothed by a plastic smoothing action or frictionalpolishing action using an abrasive agent such as a coated abrasive orabrasive grains. In the chemical treatment, chemical etching isperformed using an agent on the object to be treated.

Here, an example of performing grinding treatment on the surface of thesubstrate 101 using a grinding means 104 is described. Note thatpolishing treatment is preferably further performed on the surface ofthe substrate 101 after the grinding treatment, and a surface shape ofthe substrate 101 can be uniformed by performing the polishing treatmentafter the grinding treatment. In addition, the substrate may be thinnedor removed by further performing etching using chemical treatment afterperforming either or both grinding treatment and polishing treatment. Inparticular, in the case of removing the substrate 101, the substrate 101can be efficiently removed by performing etching by chemical treatmentafter thinning the substrate to some extent by performing any or all ofgrinding treatment, polishing treatment, and the like. Note that in thecase of using a glass substrate as the substrate 101, chemical etchingusing a drug solution containing a hydrofluoric acid is preferablyperformed as the chemical treatment. Note that in the case of thinningthe substrate 101, the substrate 101 is preferably thinned to athickness of 1 μm to 100 μm, preferably, 2 μm to 50 μm, more preferably,4 to 30 μm, so that the substrate has flexibility. In addition, in thecase of removing the substrate 101, the substrate is preferably removedcompletely, but the substrate may have a thickness of 1 μm or less.

In addition, in the case of removing the substrate 101, the insulatingfilm 102 which is provided over the substrate 101 as a protective filmcan be used as a stopper by utilizing an etching selection ratio of thesubstrate 101 to the insulating film 102. For example, in the case ofusing a glass substrate as the substrate 101 and forming a nitridedlayer by performing high-density plasma treatment on the glass substratein a nitrogen atmosphere, physical strength of the nitrided layer isimproved since the nitrided layer contains more nitrogen than the glasssubstrate on which nitriding treatment is not performed. Therefore, thenitrided layer can be utilized as a grinding or polishing stopper ingrinding or polishing to remove the substrate 101. In addition, thenitrided layer can also be utilized as a stopper utilizing an etchingselection ratio by chemical treatment similarly in the case of removingthe substrate 101.

Through the above steps, a flexible semiconductor device can bemanufactured (FIG. 1E). Thereafter, a semiconductor device may becompleted by further sealing the element group 103 with a flexible filmor the like in accordance with applications, which can be appropriatelydetermined by a practitioner.

Thus, in the semiconductor device shown in FIGS. 1A to 1E, the elementgroup 103 can be prevented from being mixed with an impurity elementsince the insulating film 102 functioning as a protective film is formedeven after thinning the substrate 101.

Subsequently, the case of performing surface treatment, after thinning asubstrate, on the thinned substrate is explained with reference to FIGS.2A to 2E.

First, a substrate 101 is prepared, and its surface is washed usinghydrofluoric acid (HF), or alkaline or pure water (FIG. 2A). As thesubstrate 101, any of the above-mentioned substrates may be used.

Next, an element group 103 including a semiconductor element such as atransistor is formed over the substrate 101 (FIG. 2B).

Then, the substrate 101 is thinned by grinding, polishing, or etching asurface of the substrate 101 (a side opposite to a side to be providedwith the element group 103) to form a substrate 106 (FIG. 2C). Here, anexample of grinding the surface of the substrate 101 using a grindingmeans 104 is described. A surface shape of the substrate 101 can beuniformed by further polishing the surface of the substrate 101 aftergrinding. In addition, the substrate may be thinned by furtherperforming etching using chemical treatment after performing either orboth grinding treatment and polishing treatment.

Next, surface treatment is performed on the thinned substrate 106 (FIG.2E). The surface treatment can be performed using any of theabove-mentioned methods, but the surface treatment here is preferablyperformed using high-density plasma treatment. An insulating filmfunctioning as a protective film can be provided using a CVD method, asputtering method, or the like. However, in the case of using the abovemethod, the element group 103 that is an object to be treated may bedamaged due to the influence of treatment temperature or the like, andcharacteristics of a transistor or the like included in the elementgroup 103 may be adversely affected. On the other hand, in the case ofperforming high-density plasma treatment, plasma density is high andelectron temperature in the vicinity of the object to be treated is low.Therefore, damage by plasma to the object to be treated can besuppressed. In addition, because of low plasma electron temperature, thenitriding treatment, the oxidizing treatment, or the like can beperformed at lower temperature as compared to conventional plasmatreatment or thermal oxidizing method. In addition, because of highplasma density, the nitrided layer, the oxidized layer, or the likeformed by performing nitriding treatment or oxidizing treatment on theobject to be treated with the use of plasma treatment is superior inuniformity of thickness or the like to the film formed by a CVD method,a sputtering method, or the like, and a dense film can be formed. Thus,for example, a nitrided layer 107 (hereinafter also referred to as an“insulating layer 107”) which functions as a protective film is formedon the surface of the substrate 106 by performing high-density plasmatreatment on the surface of the substrate 106 in a nitrogen atmosphere.In this case, the treated object (here, the insulating film 107 formedon the surface of the substrate 106) may contain a noble gas which isused for the plasma treatment, and for example, in the case of using Ar,the treated object may contain Ar. Note that the substrate 106 in astate where the insulating film 107 functioning as a protective film isformed is preferably thinned to a thickness of 1 μm to 100 μm,preferably, 2 μm to 50 μm, more preferably, 4 μm to 30 μm, so that thesubstrate has flexibility.

Thus, the element group 103 can be prevented from being mixed with animpurity element by forming the insulating film 107 functioning as aprotective film on the surface of the thinned substrate 106 afterthinning the substrate 101.

In addition, the substrate 101 can be thinned after forming theinsulating film 102 functioning as a protective film as shown in FIGS.1A to 1E, and the insulating film 107 functioning as a protective filmcan further be formed over the thinned substrate 106 as shown in FIGS.2A to 2E. For example, N atoms can be added to one surface of thesubstrate 101 by doping before thinning the substrate 101 to form thenitrided layer 102 (the insulating film 102) on the surface of thesubstrate 101; the other side of the substrate 101 can be thinned afterforming an element group of a transistor or the like over the substrate101 with the insulating film 102 interposed therebetween; and thenitrided layer 107 (insulating film 107) can be formed by performinghigh-density plasma treatment on the thinned side of the substrate 101in a nitrogen atmosphere. Alternatively, the nitrided layer 102(insulating film 102) can be formed by performing high-density plasmatreatment on one side of the substrate 101 in a nitrogen atmospherebefore thinning the substrate 101; the other side of the substrate 101can further be thinned after forming an element group of a transistor orthe like over the substrate 101 with the insulating film 102 interposedtherebetween; and an insulating film functioning as a protective filmcan be formed by performing high-density plasma treatment on the thinnedside of the substrate 101.

Note that high-density plasma treatment is preferably employed as thesurface treatment in the case of performing surface treatment on asubstrate provided with an element group including a semiconductorelement such as a transistor (here, in the case of performing surfacetreatment after thinning the substrate). This is because damage to theelement group 103 during the surface treatment can be suppressed byemploying high-density plasma treatment. On the other hand, in the caseof performing surface treatment on a substrate that is not provided withan element group including a semiconductor element such as a transistor(here, in the case of performing surface treatment before thinning thesubstrate), damage to the element group or the like does not need to beconsidered. Therefore, a method such as high-density plasma treatment,doping with an impurity element, thermal oxidizing treatment in anitrogen atmosphere, an oxygen atmosphere, or the like, a CVD method, ora sputtering method can be used for the surface treatment.

As described above, the insulating film 102 and the insulating film 107which function as protective films can be formed by performing surfacetreatment before thinning the substrate 101 and after thinning thesubstrate 101. Therefore, the element group 103 can be more effectivelyprevented from being mixed with an impurity element from outside.

As described above, even in the case of thinning a substrate, the entryof an impurity element, moisture, or the like into a semiconductorelement provided over the substrate can be suppressed by forming aprotective film by performing surface treatment such as plasma treatmenton the substrate before and after thinning the substrate.

Hereinafter, explanation is made on specific examples of theabove-described manufacturing methods in FIGS. 1A to 1E and FIGS. 2A to2E.

Embodiment Mode 1

In this embodiment mode, an example of a method for manufacturing asemiconductor device of the present invention is explained withreference to FIGS. 3A to 4C. Initially, the above-describedmanufacturing method in FIGS. 1A to 1E is explained in more detail.

First, a substrate 201 is prepared, and a surface of the substrate 201is washed using hydrofluoric acid (HF), or alkaline or pure water (FIG.3A).

As the substrate 201, a glass substrate of barium borosilicate glass,aluminoborosilicate glass, or the like, a quartz substrate, a ceramicsubstrate, a metal substrate including stainless steel, a semiconductorsubstrate of Si or the like, or the like can be used. Note that the caseof using a glass substrate as the substrate 201 is described here.

Next, nitriding treatment is performed on one side of the substrate 201by plasma treatment to form a nitrided layer 202 (hereinafter alsoreferred to as an “insulating film 202”) on the surface of the substrate201 (FIG. 3B). The insulating film 202 contains at least nitride, andthe nitride formed on the substrate may exist so as to have aconcentration distribution (here, a concentration distribution ofnitrogen) depending on conditions of surface treatment. Instead ofplasma treatment, the insulating film 202 can be formed on the substrate201 by doping with N atoms. Further, in the case of performing plasmatreatment, the above-mentioned high-density plasma treatment ispreferably performed. The high-density plasma treatment can be performedat low electron temperature and with high density; therefore, damage tothe surface of the substrate 201 can be reduced, and the surface can bedensified.

By performing the high-density plasma treatment on an object to betreated, damage by plasma to the object to be treated can be suppressedsince plasma density is high and electron temperature in the vicinity ofthe object to be treated is low. In addition, because of high plasmadensity, a nitrided layer, a oxidized layer, or the like formed byperforming nitriding treatment or oxidizing treatment on the object tobe treated with the use of plasma treatment is superior in uniformity ofthickness or the like to a film formed by a CVD method, a sputteringmethod, or the like, and a dense film can be formed. In addition,because of low plasma electron temperature, the nitriding treatment, theoxidizing treatment, or the like can be performed at lower temperaturethan conventional plasma treatment or thermal oxidizing method. In thecase of using a glass substrate as the substrate 201, the nitridingtreatment or oxidizing treatment can be performed sufficiently even whenthe plasma treatment is performed at a temperature lower by 100° C. ormore than a strain point of the glass substrate.

Next, a base insulating film 203 (hereinafter also referred to as an“insulating film 203”) which functions as a base film is formed over theinsulating film 202, and a semiconductor film 204 is formed over theinsulating film 203 (FIG. 3C).

The insulating film 203 can be provided with a single-layer structure ofan insulating film containing oxygen and/or nitrogen such as a siliconoxide (SiO_(X)) film, a silicon nitride (SiN_(X)) film, a siliconoxynitride (SiO_(X)N_(Y)) (X>Y) film, or a silicon nitride oxide(SiN_(X)O_(Y)) (X>Y) film or a stacked structure thereof. For example,in the case where the insulating film 203 has a two-layer structure, asilicon nitride oxide film may be provided as a first layer of theinsulating film and a silicon oxynitride film may be provided as asecond layer of the insulating film. In the case where the insulatingfilm 203 has a three-layer structure, a silicon oxynitride film may beprovided as a first layer of the insulating film, a silicon nitrideoxide film is provided as a second layer of the insulating film, and asilicon oxynitride film may be provided as a third layer of theinsulating film. Thus, the formation of the insulating film 203functioning as a base film can suppress the diffusion of alkali metalsuch as Na or alkaline earth metal into the semiconductor film 204 fromthe substrate 201 and the adverse effect thereof on characteristics of asemiconductor element.

The semiconductor film 204 can be formed with an amorphous semiconductoror a semi-amorphous semiconductor (SAS). Alternatively, apolycrystalline semiconductor film may be used. The SAS has anintermediate structure between an amorphous structure and a crystallinestructure (including a single crystal and a polycrystal) and a thirdstate which is stable in terms of free energy, and it includes acrystalline region having short-range order and lattice distortion. Inat least a part of a region of the film, a crystal region of 0.5 nm to20 nm can be observed. In the case of containing silicon as a maincomponent, a Raman spectrum due to L-O phonon is shifted to a lowerwavenumber side than 520 cm⁻¹. A diffraction peak of (111) or (220) tobe caused by a crystal lattice of silicon is observed in X-raydiffraction. Hydrogen or halogen of at least 1 atomic % or more iscontained to terminate a dangling bond. The SAS is formed by performingglow discharge decomposition (plasma CVD) on a gas containing silicon.SiH₄ is given as the gas containing silicon. In addition, Si₂H₆,SiH₂Cl₂, SiHCl₃, SiCl₄, SiF₄, or the like can also be used as the gascontaining silicon. In addition, GeF₄ may be mixed. The gas containingsilicon may be diluted with H₂, or H₂ and one or more noble gas elementsof He, Ar, Kr, and Ne. A dilution ratio thereof may range from 2 timesto 1000 times; pressures, approximately 0.1 Pa to 133 Pa; and powersupply frequency, 1 MHz to 120 MHz, preferably, 13 MHz to 60 MHz. Asubstrate heating temperature may be 300° C. or less. A concentration ofan atmospheric constituent impurity such as oxygen, nitrogen, or carbon,as an impurity element in the film, is preferably 1×10²⁰ atoms/cm³ orless; in particular, a concentration of oxygen is 5×10¹⁹ atoms/cm³ orless, preferably 1×10¹⁹ atoms/cm³ or less. Here, an amorphoussemiconductor film is formed with a material containing silicon (Si) asits main component (such as Si_(X)Ge_(1-X)) using a sputtering method,an LPCVD method, a plasma CVD method, or the like, and the amorphoussemiconductor film is crystallized by a laser crystallization method, athermal crystallization method using RTA or an annealing furnace, athermal crystallization method using a metal element which promotescrystallization, or the like. In addition, the crystallization may beperformed by generating thermal plasma by application of a DC bias andapplying the thermal plasma to the semiconductor film.

Next, the semiconductor film 204 is selectively etched to formisland-like semiconductor films 205 a to 205 d, and a gate insulatingfilm 206 is formed to cover the island-like semiconductor films 205 a to205 d (FIG. 3D).

The gate insulating film 206 can be provided by a CVD method, asputtering method, or the like to have a single-layer structure of aninsulating film containing oxygen and/or nitrogen such as a siliconoxide (SiO_(X)) film, a silicon nitride (SiN_(X)) film, a siliconoxynitride (SiO_(X)N_(Y)) (X>Y) film, or a silicon nitride oxide(SiN_(X)O_(Y)) (X>Y) film or a laminated structure thereof.Alternatively, the gate insulating film can be formed by performingoxidizing treatment or nitriding treatment on the surface of theisland-like semiconductor films 205 a to 205 d by performinghigh-density plasma treatment on the island-like semiconductor films 205a to 205 d in an oxygen atmosphere (for example, an atmospherecontaining oxygen (O₂) and a noble gas (including at least one of He,Ne, Ar, Kr, and Xe) or an atmosphere containing oxygen, hydrogen (H₂),and a noble gas) or a nitrogen atmosphere (for example, an atmospherecontaining nitrogen (N₂) and a noble gas (including at least one of He,Ne, Ar, Kr, and Xe) or an atmosphere containing NH₃ and a noble gas). Byperforming oxidizing treatment or nitriding treatment on the surface ofthe island-like semiconductor films 205 a to 205 d by high-densityplasma treatment, a gate insulating film can be formed. The gateinsulating film formed with an oxidized layer or a nitrided layer formedby performing oxidizing treatment or nitriding treatment on theisland-like semiconductor films 205 a to 205 d by high-density plasmatreatment is superior in uniformity of thickness or the like to aninsulating film formed by a CVD method, a sputtering method, or the likeand has a dense film.

Next, a gate electrode 207 is selectively formed over the gateinsulating film 206 and thereafter an insulating film 209 and aninsulating film 211 are formed to cover the gate electrode 207. Notethat a diagram is made here on an example of forming a side wall(hereinafter also an “insulating film 208”) to be in contact with a sideof the gate electrode 207 and providing LDD regions in the semiconductorfilms 205 a and 205 c located below the insulating film 208 in theN-channel thin film transistors 210 a and 210 c. (FIG. 3E)

The gate electrode 207 can be provided by a CVD method, a sputteringmethod, or the like with a single-layer structure or a laminatedstructure of an element selected from tantalum (Ta), tungsten (W),titanium (Ti), molybdenum (Mo), aluminum (Al), copper (Cu), chromium(Cr), niobium (Nb), and the like or an alloy material or a compoundmaterial containing the element as its main component. Alternatively,the gate electrode 207 can be formed with a semiconductor materialtypified by polycrystalline silicon which is doped with an impurityelement such as phosphorus. For example, the gate electrode can beprovided with a laminated structure of tantalum nitride and tungsten.

The insulating film 209 can be provided by a CVD method, a sputteringmethod, or the like to have a single-layer structure of an insulatingfilm containing oxygen and/or nitrogen such as a silicon oxide (SiO_(X))film, a silicon nitride (SiN_(X)) film, a silicon oxynitride(SiO_(X)N_(Y)) (X>Y) film, or a silicon nitride oxide (SiN_(X)O_(Y))(X>Y) film or a film containing carbon such as a DLC (diamond likecarbon) film or a laminated structure thereof.

The insulating film 211 can be provided by a CVD method, a sputteringmethod, or the like with a single-layer structure of an insulating filmcontaining oxygen and/or nitrogen such as a silicon oxide (SiO_(X))film, a silicon nitride (SiN_(X)) film, a silicon oxynitride(SiO_(X)N_(Y)) (X>Y) film, or a silicon nitride oxide (SiN_(X)O_(Y))(X>Y) film or a film containing carbon such as a DLC (diamond likecarbon) film, an organic material such as epoxy, polyimide, polyamide,polyvinyl phenol, benzocyclobutene, or acrylic, or a siloxane resin.Note that the siloxane resin corresponds to a resin having Si—O—Sibonds. Siloxane has a skeleton formed from a bond of silicon (Si) andoxygen (O). As a substituent, an organic group containing at leasthydrogen (for example, an alkyl group or aromatic hydrocarbon) is used.As a substituent, a fluoro group can also be used. Alternatively, anorganic group containing at least hydrogen and a fluoro group may beused as a substituent. Note that in the semiconductor device in FIG. 3E,the insulating film 211 can be provided directly to cover the gateelectrode 207 without providing the insulating film 209.

Next, a conductive film 212 is formed to electrically connect to asource region and a drain region of the island-like semiconductor films205 a to 205 d over the insulating film 211, and an insulating film 213is formed to cover the conductive film 212 (FIG. 4A). Thereby, thin filmtransistors 210 a to 210 d (hereinafter also referred to as N-channelthin film transistors 210 a and 210 c and P-channel thin film transistor210 b and 210 d) are provided.

The conductive film 212 can be formed using a single-layer structure ora laminated structure of an element selected from aluminum (Al),tungsten (W), titanium (Ti), tantalum (Ta), molybdenum (Mo), nickel(Ni), platinum (Pt), copper (Cu), gold (Au), silver (Ag), manganese(Mn), neodymium (Nd), and carbon (C) or an alloy containing a pluralityof the elements. For a conductive film formed of an alloy containing aplurality of the elements, an Al alloy containing C and Ti, an Al alloycontaining Ni, an Al alloy containing C and Ni, an Al alloy containing Cand Mn, or the like can be used. In addition, in the case of providingwith a laminated structure, a laminated layer of Al and Ti can beprovided.

The insulating film 213 can be provided by a CVD method, a sputteringmethod, or the like with a single-layer structure of an insulating filmcontaining oxygen and/or nitrogen such as a silicon oxide (SiO_(X))film, a silicon nitride (SiN_(X)) film, a silicon oxynitride(SiO_(X)N_(Y)) (X>Y) film, or a silicon nitride oxide (SiN_(X)O_(Y))(X>Y) film or a film containing carbon such as a DLC (diamond likecarbon) film, an organic material such as epoxy, polyimide, polyamide,polyvinyl phenol, benzocyclobutene, or acrylic, or a siloxane resin.

Next, the substrate 201 is thinned or removed by performing grindingtreatment, polishing treatment, etching by chemical treatment, or thelike on the other surface of the substrate 201 (a side opposite to theside provided with the insulating film 202) (see FIG. 4B). Here, anexample of grinding the surface of substrate 201 using a grinding means214 is described. Further, the surface of the substrate 201 ispreferably further subjected to polishing treatment after grinding, andthe surface shape of the substrate 201 can be unformed by performingpolishing treatment after grinding treatment. Alternatively, thesubstrate may be thinned or removed by performing etching using chemicaltreatment after performing either or both grinding treatment andpolishing treatment. Particularly in the case of removing the substrate201, the substrate 201 can be efficiently removed by performing etchingby chemical treatment after thinning the substrate to some extent byperforming any or all of grinding treatment, polishing treatment, andthe like.

Through the above-described steps, a flexible semiconductor device canbe obtained (FIG. 4C).

Note that the structure of the thin film transistor included in thesemiconductor device of the present invention is not limited to thatdescribed above. For example, in FIG. 3E, the LDD regions are providedin the semiconductor films located below the sidewalls of the N-typethin film transistors 210 a and 210 c, and the LDD regions are notprovided in the P-type thin film transistors 210 b and 210 d. However,the LDD regions may be provided in both of them, or the LDD regions andthe sidewalls may be provided in neither of them (FIG. 7A). In addition,the structure of the thin film transistor is not limited to thosedescribed above, and the structure may be a single gate structure inwhich one channel formation region is formed, a multi-gate structuresuch as a double gate structure where two channel formation regions areformed or a triple gate structure where three channel formation regionare formed. In addition, the structure may be a bottom gate structure ora dual gate structure including two gate electrodes positioned above andbelow a channel formation region with each a gate insulating filminterposed therebetween. In addition, in the case of forming the gateelectrode to have a laminated structure, the gate electrode can have astructure where the gate electrode is provided with a first conductivefilm 207 a fowled in a lower part of the gate electrode and a secondconductive film 207 b formed over the first conductive film 207 a; thefirst conductive film 207 a is formed to have a tapered shape; and animpurity region having a lower concentration than the impurity regionfunctioning as a source or drain region is provided so as to overlapwith only the first conductive film (FIG. 7B). In addition, in the caseof forming the gate electrode to have a laminated structure, the gateelectrode can have a structure where the gate electrode is provided withthe first conductive film 207 a formed in a lower part of the gateelectrode and the second conductive film 207 b formed over the firstconductive film 207 a; sidewalls 208 are formed so as to be in contactwith a side wall of the second conductive film 207 b and formed abovethe first conductive film 207 a (FIG. 7C). In the above structure, animpurity region functioning as a source or drain region of thesemiconductor film can also be formed with silicide of Ni, Co, W, Mo, orthe like.

Subsequently, an example of a method for manufacturing a semiconductordevice, which is different from that in FIGS. 3A to 4C, is explainedwith reference to FIGS. 5A to 5D. Specifically, the above-describedmanufacturing method in FIGS. 2A to 2E is explained in more detail.

First, formation is performed as described above to the state shown inFIG. 4A. However, the insulating film 203 is directly formed here on thesubstrate 201 without performing surface treatment on the surface of thesubstrate 201 (FIG. 5A).

Next, the substrate 201 is thinned by performing any or all of grindingtreatment, polishing treatment, etching by chemical treatment, and thelike on one surface of the substrate 201 (a side opposite to the sideprovided with the insulating film 203) to form a substrate 216 (FIG.5B). Here, an example of grinding the surface of the substrate 201 usinga grinding means 214 is described. In addition, the surface shape of thesubstrate 201 can be uniformed by polishing the surface of the substrate201 after grinding.

Next, surface treatment is performed on the thinned substrate 216 toform an insulating film functioning as a protective film (FIG. 5D). Thesurface treatment can be performed by using any of the above-mentionedmethods, but here the surface treatment is preferably performed on thesubstrate 216 using high-density plasma treatment. An insulating film217 functioning as a protective film can be provided using a CVD method,a sputtering method, or the like. However, in the case of using theabove method, thin film transistors 210 a to 210 d and the like that areobjects to be treated may be damaged due to the influence of treatmenttemperature or the like, and characteristics of the thin filmtransistors 210 a to 210 d may be adversely affected. On the other hand,in the case of performing high-density plasma treatment, plasma densityis high and electron temperature in the vicinity of the object to betreated is low. Therefore, damage by plasma to the thin film transistors210 a to 210 d and the like which are objects to be treated can besuppressed. In addition, because of high plasma density, a nitridedlayer, an oxidized layer, or the like formed by performing nitridingtreatment or oxidizing treatment on the object to be treated with theuse of plasma treatment is superior in uniformity of thickness or thelike to a film formed by a CVD method, a sputtering method, or the like,and a dense film can be formed. Here, a nitrided layer 217 (hereinafteralso referred to as an “insulating film 217”) which functions as aprotective film is formed on the surface of the substrate 216 byperforming high-density plasma treatment on the surface of the substrate216 in a nitrogen atmosphere. In this case, the treated object (here,the insulating film 217 formed on the surface of the substrate 216) maycontain a noble gas which is used for the plasma treatment, and forexample, the treated object may contain Ar in the case of using Ar.

In addition, the semiconductor device of the present invention is notlimited to the structures shown in FIGS. 3A to 5D, and can have, forexample, structures shown in FIGS. 6A and 6B. The structure shown inFIG. 6A is a structure in which the substrate 201 is thinned in FIG. 4Bso as to remain as a substrate 218 without being completely removed. Inaddition, the structure shown in FIG. 6A can be a structure in whichsurface treatment is performed on the surface of the substrate 218 (aside opposite to the side provided with the insulating film 202) toprovide the insulating film 217 functioning as a protective film, asshown in FIG. 6B. In this case, the structure is a laminated structureof the insulating film 202 functioning as a protective film, thesubstrate 216, and the insulating film 217; therefore, the structure canmore effectively prevent an impurity element, moisture, or the like frombeing mixed into a thin film transistor from outside. For example, inthe case where the insulating film 202 and the insulating film 217functioning as protective films are formed by performing nitridingtreatment on a glass substrate, silicon oxide which form the substrateis sandwiched between nitrided layers in the structure of FIG. 6B.

In addition, the semiconductor device of the present invention can beapplied to a semiconductor device which can transmit and receive datawithout contact (also referred to as an RFID (Radio FrequencyIdentification) tag, an ID tag, an IC tag, an IC chip, an RF (RadioFrequency) tag, a wireless tag, an electronic tag, or a wireless chip)and a display device including a pixel portion.

For example, in FIGS. 4A to 4C, a conductive film 221 functioning as anantenna is formed over the insulating film 213, an insulating film 222functioning as a protective film is formed to cover the conductive film221, before thinning or removing the substrate 201 and subsequently, thesubstrate 201 is thinned or removed, thereby manufacturing a flexiblesemiconductor device which can transmit and receive data without contact(FIG. 8A).

The conductive film 221 is formed of a conductive material by using aCVD method, a sputtering method, a printing method such as screenprinting or gravure printing, a droplet discharge method, a dispensermethod, a plating method, or the like. The conductive material is anelement selected from aluminum (Al), titanium (Ti), silver (Ag), copper(Cu), gold (Au), and nickel (Ni) or an alloy material or a compoundmaterial containing the element as its main component, and theconductive film is formed to have a single-layer structure or alaminated structure of the conductive material.

In addition, a flexible semiconductor device which can transmit andreceive data without contact can be manufactured by attaching asubstrate 223 provided with the conductive film 221 functioning as theantenna to a semiconductor element such as a thin film transistorprovided over the substrate 201 so as to be electrically connected toeach other before thinning or removing the substrate 201, andsubsequently thinning or removing the substrate 201 (FIG. 8B).

For the substrate 223, an originally flexible material such as plasticmay be used, or both the substrate 201 and the substrate 223 can bethinned or removed after being attached to each other; in the lattercase, a material similar to the substrate 201 can be used for thesubstrate 223. In attaching the substrate 201 and the substrate 223,here, the semiconductor element and the conductive film 221 functioningas the antenna are connected to each other using conductive particles225 included in an adhesive resin 224. Alternatively, they can beconnected to each other using a conductive adhesive such as silverpaste, copper paste, or carbon paste, an anisotropic conductive adhesivesuch as ACP (Anisotropic Conductive Paste), solder joint, or the like.

In addition, a semiconductor device including a pixel portion can bemanufactured by providing a pixel electrode 231 over the insulating film211 so as to be electrically connected to the conductive film 212 beforethinning or removing the substrate 201 in FIGS. 4A to 4C. For example, aflexible liquid crystal display device can be manufactured by providinga liquid crystal material 233 over the pixel electrode 231 so as to besandwiched between an orientation film 232 and an orientation film 234,and providing an opposite electrode 235 over the orientation film 234(FIG. 8C). In addition, a flexible self-light emitting type displaydevice can be manufactured by continuously laminating a light emittinglayer 236 such as an organic EL layer and an opposite electrode 237 overthe pixel electrode 231 (FIG. 8D). Note that in FIG. 8D, an insulatingfilm 238 is provided as a partition for separating a plurality ofpixels, and an insulating film 239 is provided as a protective film.

Note that this embodiment mode describes the example of using a thinfilm transistor as an element group in FIGS. 1A to 1E or FIGS. 2A to 2E,but this embodiment mode is not limited thereto. As described above, afield effect transistor (PET) using a semiconductor substrate of Si orthe like as a channel, an organic TFT using an organic material as achannel, or the like can be used. Furthermore, a diode, a solar cell, orthe like can be provided besides the transistor.

For example, in the case of using a semiconductor substrate of Si or thelike as the substrate 201, after forming a transistor using thesemiconductor substrate as a channel region over one side of thesubstrate 201 and thinning the substrate 201 from the other side,surface treatment is performed on the surface of the thinned substrate201 to form an insulating film functioning as a protective film. Thesurface treatment can be performed using any of the above-mentionedmethods, but high-density plasma treatment is preferably performed sincedamage to the transistor can be suppressed.

Note that this embodiment mode can be freely combined with anotherembodiment mode described in this specification.

Embodiment Mode 2

In this embodiment mode, an example of an apparatus in the case ofperforming plasma treatment in the above embodiment mode is explainedwith reference to drawings.

A plasma treatment apparatus shown in FIG. 19A includes a plurality oftreatment chambers capable of generating plasma, a common chamber fortransferring a substrate to each chamber, and a load lock chamber fortaking in or out the substrate. Thus, in the case of continuouslyperforming formation of an insulating film, a conductive film, or asemiconductor film and plasma treatment thereof, a plasma treatmentapparatus including a plurality of treatment chambers can be used. Notethat FIG. 19A is a top plan view showing one exemplary structure of aplasma treatment apparatus described in this embodiment mode.

The plasma treatment apparatus shown as an illustrative example in FIG.19A includes a first treatment chamber 311, a second treatment chamber312, a third treatment chamber 313, a fourth treatment chamber 314, loadlock chambers 310 and 315, and a common chamber 320. Each treatmentchamber has airtightness. Each treatment chamber is provided with avacuum evacuation means, a gas introduction means, and a plasmageneration means.

The load lock chambers 310 and 315 are chambers for transferring asample (substrate to be treated) to each chamber. The common chamber 320is provided in common for each of the load lock chambers 310 and 315 andthe first to fourth treatment chambers 311 to 314. A substrate 201 istransferred to each treatment chamber from the load lock chambers 310and 315 via the common chamber 320. The first to fourth treatmentchambers are chambers for performing formation treatment of a conductivefilm, an insulating film, or a semiconductor film, etching treatment,plasma treatment, or the like on the substrate 201. Note that the commonchamber 320 is provided with a robot arm 321, with which the substrate201 is transferred to each chamber.

Gate valves 322 to 327 are respectively provided between the commonchamber 320 and the first treatment chamber 311, the second treatmentchamber 312, the third treatment chamber 313, the fourth treatmentchamber 314, and the load lock chambers 310 and 315.

The first treatment chamber 311, the second treatment chamber 312, thethird treatment chamber 313, and the fourth treatment chamber 314 havedifferent internal structures in accordance with the intended use. Asthe kind of treatment, there is plasma treatment, film formationtreatment, heat treatment, etching treatment, or the like.

FIG. 19B shows an exemplary internal structure of the treatment chamberfor performing plasma treatment. The inside of the treatment chamber isprovided with a supporting base 351 for positioning a substrate 331 tobe subjected to plasma treatment, a gas supply portion 352 forintroducing a gas, an exhaust outlet 353, an antenna 354, a dielectricplate 355, and a high-frequency supply portion 356 for supplying a highfrequency wave for generating plasma. In addition, the temperature ofthe substrate to be treated 331 can be controlled by providing thesupporting base 351 with a temperature control portion 357. An exampleof the plasma treatment is explained below.

Here, plasma treatment includes oxidizing treatment, nitridingtreatment, oxynitriding treatment, hydrogenating treatment, and surfacemodification treatment on a semiconductor film, an insulating film, or aconductive film. Such treatment may be performed by selecting anappropriate gas in accordance with the intended use.

For example, the oxidizing treatment or nitriding treatment may beperformed in the following manner. First, the treatment chamber isevacuated, and a gas containing oxygen or nitrogen is introduced fromthe gas supply portion 352. As the gas containing oxygen, for example, amixed gas of oxygen (O₂) and a noble gas or a mixed gas of oxygen,hydrogen, and a noble gas can be introduced. In addition, as the gascontaining nitrogen, a mixed gas of nitrogen and a noble gas or a mixedgas of an ammonia gas and a noble gas can be introduced. Next, thesubstrate to be treated 331 is placed on the supporting base 351including the temperature control portion 357, and the substrate to betreated 331 is heated to a temperature of 100° C. to 550° C. Note thatthe distance between the substrate to be treated 331 and the dielectricplate 355 are set to be in the range of 20 mm to 80 mm (preferably, 20mm to 60 mm).

Next, a microwave is supplied to the antenna 354 from the high-frequencysupply portion 356. Here, a microwave with a frequency of 2.45 GHz issupplied. By introducing the microwave into the treatment chamberthrough the dielectric plate 355 from the antenna 354, high-densityplasma 358 which is activated by plasma excitation is generated. Whenplasma excitation is performed by introducing a microwave, plasma withhigh electron density (of 1×10¹¹ cm⁻³ or more) can be generated at lowelectron temperature (of 3 eV or less, preferably, 1.5 eV or less). Withan oxygen radical (which may contain an OH radical) or a nitrogenradical (which may contain an NH radical) generated by suchlow-electron-temperature and high-density plasma, nitriding treatment oroxidizing treatment can be performed without damaging the substrate tobe treated 331 by performing plasma treatment on the surface of thesubstrate to be treated 331.

For example, in the case of performing plasma treatment in an atmospherecontaining an NH₃ gas and an Ar gas, high-density excited plasma inwhich an NH₃ gas is mixed with an Ar gas is generated with a microwave.In the high-density excited plasma in which an NH₃ gas is mixed with anAr gas, a radical is produced by excitation of the Ar gas with theintroduced microwave. The Ar radical collides with NH₃ molecules,thereby producing a nitrogen radical (which may contain an NH radical).The radical reacts with the substrate to be treated 331; accordingly,the substrate to be treated 331 can be nitrided. Thereafter, the NH₃ gasand the Ar gas are exhausted to the outside of the treatment chamberthrough the exhaust outlet 353. Meanwhile, in the case of introducingoxygen, nitrous oxide, or the like, an oxygen radical (which may containan OH radical) is produced; accordingly, the substrate to be treated 331or a coating film over the substrate to be treated 331 can be oxidized.

Also in manufacturing a transistor over the substrate 201, for example,a semiconductor film can be directly oxidized, nitrided, or oxynitridedby solid-phase reaction with such high-density plasma to form a gateinsulating film. In addition, a gate insulating film can be obtained bydepositing and stacking an insulating film formed of silicon oxide,silicon oxynitride, silicon nitride, or the like by a CVD methodutilizing plasma or thermal reaction, over the insulating film which isformed on the semiconductor film by solid-phase reaction withhigh-density plasma. In any case, a field effect transistor, which isformed to include an insulating film formed with high-density plasma ina part or the whole of the gate insulating film, can be reduced invariation of characteristics.

As a specific example, explanation is made below of an example ofperforming plasma treatment on the substrate 201 in the first treatmentchamber 311, forming the insulating film 203 in the second treatmentchamber 312, and performing plasma treatment in the third chamber 313,and forming the semiconductor film 204 in the fourth treatment chamber314 in FIGS. 3A to 3E.

First, a cassette 328, which stores a number of the substrates 201, iscarried into the load lock chamber 310. After the cassette 328 iscarried in, a loading door of the load lock chamber 310 is closed. Withthis condition, the gate valve 322 is opened to take out one substrateto be treated from the cassette 328, which is then positioned in thecommon chamber 320 with the robot arm 321. In this case, positioning ofthe substrate 201 is carried out in the common chamber 320.

Next, the gate valve 322 is closed, and the gate valve 324 is opened.Then, the substrate 201 is transferred to the first treatment chamber311. In the first treatment chamber 311, the substrate 201 is oxidizedor nitrided by performing plasma treatment on the substrate 201. Here,the nitrided layer 202 containing nitride is formed on the surface ofthe substrate 201 by performing plasma treatment in a nitrogenatmosphere in the first treatment chamber 311.

After forming the nitrided layer on the surface of the substrate 201,the substrate 201 is extracted to the common chamber 320 with the robotarm 321 and is transferred to the second treatment chamber 312. In thesecond treatment chamber 312, film formation treatment is performed at atemperature of 150° C. to 300° C. to form the insulating film 203. Theinsulating film 203 can be formed to have a single-layer structure of aninsulating film containing oxygen and/or nitrogen such as silicon oxide(SiO_(X)), silicon nitride (SiN_(X)), silicon oxynitride (SiO_(X)N_(Y))(X>Y), or silicon nitride oxide (SiN_(X)O_(Y)) (X>Y), or a laminatedstructure thereof. Here, a silicon nitride oxide film is formed as afirst layer of the insulating film, and a silicon oxynitride film isformed as a second layer of the insulating film, by a plasma CVD methodin the second treatment chamber 312. Note that the film formation methodis not limited to the plasma CVD method, and a sputtering method using atarget may be used as well.

After forming the insulating film 203, the substrate 201 is extracted tothe common chamber 320 with the robot arm 321 and is then transferred tothe third treatment chamber 313. In the third treatment chamber 313, theinsulating film 203 is oxidized or nitrided by performing plasmatreatment on the insulating film 203. Here, the surface of theinsulating film 203 is oxidized by performing plasma treatment in anoxygen atmosphere (for example, in an atmosphere containing oxygen and anoble gas, an atmosphere containing oxygen, hydrogen, and a noble gas,or an atmosphere containing dinitrogen monoxide and a noble gas) in thethird treatment chamber 313.

After oxidizing the insulating film 203, the substrate 201 is extractedto the common chamber 320 with the robot arm 321 and is then transferredto the fourth treatment chamber 314. In the fourth treatment chamber314, film formation treatment is performed at a temperature of 150° C.to 300° C. to form the semiconductor film 204 by a plasma CVD method.Note that the semiconductor film 204 may be a microcrystallinesemiconductor film, an amorphous germanium film, an amorphous silicongermanium film, a laminated film thereof, or the like. Heat treatmentfor reducing hydrogen concentration may be omitted by setting theformation temperature of the semiconductor film at 350° C. to 500° C.Note that, although the case of forming the semiconductor film by usinga plasma CVD method is described here, a sputtering method using atarget may be used as well.

In this manner, after forming the semiconductor film, the substrate 201is transferred to the load lock chamber 315 with the robot arm 321 andis stored in the cassette 329.

Note that FIG. 19A merely shows an example. For example, a conductivefilm or an insulating film may be subsequently formed using a fifthtreatment chamber after forming the semiconductor film, and the numberof treatment chambers can further be increased. In addition, separatelyfrom the treatment chamber for performing plasma treatment, a treatmentchamber for performing heat treatment such as RTA can be provided andutilized for heat treatment in a manufacturing process of asemiconductor device. In addition, FIG. 19A shows an example of usingthe first treatment chamber 311 to the fourth treatment chamber 314,each of which is a single type treatment chamber. However, a structurein which multiple substrates are treated at a time may be employed usinga batch type treatment chamber.

Note that this embodiment mode can be freely combined with the aboveembodiment mode. In other words, the material or the formation methoddescribed in the above embodiment mode can be used in combination alsoin this embodiment mode, and the material or the formation methoddescribed in this embodiment mode can be used in combination also in theabove embodiment mode.

Embodiment Mode 3

In this embodiment mode, a method for manufacturing a semiconductordevice, which is different from that in the above embodiment modes, isexplained with reference to drawings. Specifically, a method formanufacturing a semiconductor device of the present invention includinga thin film transistor, a storage element, and an antenna is explainedwith reference to drawings.

First, one surface of a substrate 701 is subjected to plasma treatmentin a nitrogen atmosphere to form a nitrided layer 702 (hereinafter alsoreferred to as an insulating film 702). Subsequently, an insulating film703 serving as a base film and an amorphous semiconductor film 704 (forexample, a film containing amorphous silicon) are formed (FIG. 9A).

As the substrate 701, a glass substrate, a quartz substrate, a metalsubstrate, or a stainless steel substrate provided with an insulatingfilm on one surface thereof, a heat-resistant plastic substrate whichcan withstand a processing temperature of the present process, or thelike may be used. Since there is no significant limitation on the areaor shape of the substrate 701, productivity can be drastically improvedwhen using, for example, a rectangular substrate having a side of onemeter or more as the substrate 701. Alternatively, a semiconductorsubstrate of Si or the like may be used.

The insulating film 703 can be provided by a CVD method, a sputteringmethod, or the like to have a single-layer structure or a multi-layerstructure of an insulating film containing oxygen and/or nitrogen suchas a silicon oxide (SiO_(X)) film, a silicon nitride (SiN_(X)) film, asilicon oxynitride (SiO_(X)N_(Y)) (X>Y) film, or a silicon nitride oxide(SiN_(X)O_(Y)) (X>Y) film. In the case where the insulating film servingas a base has a two-layer structure, for example, a silicon nitrideoxide film may be formed as a first layer and a silicon oxynitride filmmay be formed as a second layer. In the case where the insulating filmserving as the base film has a three-layer structure, a silicon oxidefilm may be formed as a first layer of the insulating film, a siliconnitride oxide film may be formed as a second layer of the insulatingfilm, and a silicon oxynitride film may be formed as a third layer ofthe insulating film. Alternatively, a silicon oxynitride film may beformed as a first layer of the insulating film, a silicon nitride oxidefilm may be formed as a second layer of the insulating film, and asilicon oxynitride film may be formed as a third layer of the insulatingfilm. The insulating film serving as the base film functions as ablocking film which prevents the entry of an impurity from the substrate701.

Subsequently, an amorphous semiconductor film 704 (for example, a filmcontaining amorphous silicon) is formed over the insulating film 703.The amorphous semiconductor film 704 is formed by a sputtering method,an LPCVD method, a plasma CVD method, or the like with a thickness of 25nm to 200 nm (preferably, 30 nm to 150 nm). Subsequently, the amorphoussemiconductor film 704 is crystallized by a known crystallization method(a laser crystallization method, a thermal crystallization method usingRTA or an annealing furnace, a thermal crystallization method using ametal element which promotes crystallization, or a combination of athermal crystallization method using a metal element which promotescrystallization and a laser crystallization method) to form acrystalline semiconductor film. Thereafter, the obtained crystallinesemiconductor film is etched into a desired shape to form crystallinesemiconductor films 706 to 710 (FIG. 9B).

An example of a manufacturing process of the crystalline semiconductorfilms 706 to 710 is briefly explained below. First, an amorphoussemiconductor film with a thickness of 66 nm is formed using a plasmaCVD method. After applying a solution containing nickel which is a metalelement for promoting crystallization so as to remain over the amorphoussemiconductor film, the amorphous semiconductor film is subjected todehydrogenating treatment (500° C. for one hour) and thermalcrystallizing treatment (550° C. for four hours) to form a crystallinesemiconductor film. Thereafter, the crystalline semiconductor film isirradiated with a laser beam, if required, to form the crystallinesemiconductor films 706 to 710 by a photolithography method.

In the case of forming a crystalline semiconductor film by a lasercrystallization method, a continuous wave laser beam (CW laser beam) ora pulsed laser beam (pulse laser beam) can be used. As a laser beamwhich can be used here, a beam emitted from one or plural kinds of a gaslaser such as an Ar laser, a Kr laser, or an excimer laser; a laserusing, as a medium, single crystalline YAG, YVO₄, forsterite (Mg₂SiO₄),YAlO₃, or GdVO₄ or polycrystalline (ceramic) YAG, Y₂O₃, YVO₄, YAlO₃, orGdVO₄ doped with one or more of Nd, Yb, Cr, Ti, Ho, Er, Tm, and Ta as adopant; a glass laser; a ruby laser; an alexandrite laser; a Ti:sapphirelaser; a copper vapor laser; and a gold vapor laser, can be used. Anobject is irradiated with a laser beam of a fundamental wave of suchlasers or a second to fourth harmonic of such a fundamental wave, sothat a crystal with a large grain size can be obtained. For example, thesecond harmonic (532 nm) or the third harmonic (355 nm) of an Nd:YVO₄laser (fundamental wave of 1064 nm) can be used. An energy density ofthe laser at this time is required to be approximately 0.01 MW/cm² to100 MW/cm² (preferably 0.1 MW/cm² to 10 MW/cm²). The irradiation isperformed with the scanning rate set at approximately 10 cm/sec to 2000cm/sec. Note that each laser using, as a medium, single crystalline YAG,YVO₄, forsterite (Mg₂SiO₄), YAlO₃, or GdVO₄ or polycrystalline (ceramic)YAG, Y₂O₃, YVO₄, YAlO₃, or GdVO₄ doped with one or more of Nd, Yb, Cr,Ti, Ho, Er, Tm, and Ta as a dopant; an Ar ion laser; and a Ti:sapphirelaser, can continuously oscillate. Further, pulse oscillation thereofcan be performed with a repetition rate of 10 MHz or more by performingQ switch operation or mode locking. When a laser beam is oscillated at arepetition rate of 10 MHz or more, a semiconductor film is irradiatedwith a next pulse during a period during the semiconductor film ismelted by the laser beam and then is solidified. Therefore, unlike thecase of using a pulsed laser having a low repetition rate, the interfacebetween the solid phase and the liquid phase can be moved continuouslyin the semiconductor film, and the semiconductor film having crystalgrains grown continuously in the scanning direction can be formed.

The crystallization of the amorphous semiconductor film using a metalelement for promoting crystallization has the advantages of enablingcrystallization at a low temperature in a short time and aligning adirection of crystals; on the other hand, the crystallization has thedisadvantage that off current is increased due to the metal elementremaining in the crystalline semiconductor film and characteristics ofthe crystalline semiconductor film are not stabilized. Therefore, anamorphous semiconductor film serving as a gettering site is preferablyformed over the crystalline semiconductor film. Since the amorphoussemiconductor film serving as a gettering site is necessary to containan impurity element such as phosphorus or argon, the amorphoussemiconductor film is preferably formed by a sputtering method by whichthe amorphous semiconductor film can contain argon at highconcentration. Thereafter, heat treatment (thermal annealing using anRTA method, an annealing furnace, or the like) is performed to diffuse ametal element into the amorphous semiconductor film. Subsequently, theamorphous semiconductor film containing the metal element is removed.This makes it possible to reduce or remove the metal element containedin the crystalline semiconductor film.

Next, a gate insulating film 705 is formed to cover the crystallinesemiconductor films 706 to 710. The gate insulating film 705 is formedby using a single layer or a laminated layer of a film containing oxideof silicon and/or nitride of silicon by a CVD method, a sputteringmethod, or the like. Specifically, the gate insulating film 705 isformed by using a single layer or a laminated layer of a film containingsilicon oxide, a film containing silicon oxynitride, or a filmcontaining silicon nitride oxide.

Alternatively, the gate insulating film 705 may be formed by performingthe above-mentioned high-density plasma treatment on the crystallinesemiconductor films 706 to 710 and oxidizing or nitriding the surface.For example, the gate insulating film 705 is formed by plasma treatmentwith an introduced mixed gas of a noble gas such as He, Ar, Kr, or Xeand oxygen, nitrogen oxide (NO₂), ammonia, nitrogen, hydrogen, or thelike. When plasma excitation in this case is performed by introducing amicrowave, high-density plasma can be produced at low electrontemperature. The surface of the semiconductor films can be oxidized ornitrided with an oxygen radical (which may contain an OH radical) or anitrogen radical (which may contain an NH radical) that is produced bythe high-density plasma.

By treatment using such high-density plasma, an insulating film with athickness of 1 nm to 20 nm, typically, 5 nm to 10 nm, is formed over thesemiconductor films. A reaction in this case is a solid-phase reaction;therefore, interface state density between the insulating film and thesemiconductor films can be extremely lowered. Since such high-densityplasma treatment directly oxidizes (or nitrides) the semiconductor films(of crystalline silicon or polycrystalline silicon), variation inthickness of the insulating film to be formed can be ideally suppressedsignificantly. Furthermore, oxidation is not performed strongly also ata crystal grain boundary of crystalline silicon, which leads to anextremely preferable state. In other words, when each surface of thesemiconductor films is subjected to solid-phase oxidation by thehigh-density plasma treatment shown here, an insulating film with lowinterface state density and favorable uniformity can be formed withoutcausing abnormal oxidation reaction at a crystal grain boundary.

As the gate insulating film, only an insulating film formed byhigh-density plasma treatment may be used. In addition, an insulatingfilm of silicon oxide, silicon oxynitride, or silicon nitride may bedeposited or laminated thereover by a CVD method utilizing plasma or athermal reaction. In either case, a transistor which is formed toinclude an insulating film formed with high-density plasma in a part orthe whole of the gate insulating film can reduce variations incharacteristics.

The crystalline semiconductor films 706 to 710, which are formed bycrystallizing the semiconductor film by irradiation with a continuouswave laser beam or a laser beam oscillated at a repetition rate of 10MHz or more while scanning the semiconductor film with the laser beam inone direction, have a feature that crystals grow in a scanning directionof the laser beam. When transistors are arranged such that the scanningdirection is aligned with each a channel length direction (a directionin which carries flow when a channel formation region is formed) and thetransistor is combined with the gate insulating film, transistors (TFTs)with little variation in characteristics and high electron field-effectmobility can be obtained.

Next, a first conductive film and a second conductive film are laminatedover the gate insulating film 705. The first conductive film is formedby a plasma CVD method, a sputtering method, or the like with athickness of 20 nm to 100 nm. The second conductive film is formed by aknown method with a thickness of 100 nm to 400 nm. The first conductivefilm and the second conductive film are formed with an element selectedfrom tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo),aluminum (Al), copper (Cu), chromium (Cr), niobium (Nb), and the like;or an alloy material or a compound material containing the element asits main component. Alternatively, the first conductive film and thesecond conductive film are formed with a semiconductor material typifiedby polycrystalline silicon doped with an impurity element such asphosphorus. As an example of a combination of the first conductive filmand the second conductive film, a tantalum nitride (TaN) film and atungsten (W) film, a tungsten nitride (WN) film and a tungsten film, amolybdenum nitride (MoN) film and a molybdenum (Mo) film, or the likecan be given. Since tungsten and tantalum nitride have high heatresistance, heat treatment for thermal activation can be performed afterforming the first conductive film and the second conductive film. In thecase of not a two-layer structure but a three-layer structure, alaminated structure of a molybdenum film, an aluminum film, and amolybdenum film may be employed.

Next, a mask of resist is formed using a photolithography method andetching treatment for forming a gate electrode and a gate line isperformed to form conductive films 716 to 725 functioning as gateelectrodes.

Then, a mask of resist is formed by a photolithography method and animpurity element which imparts N-type conductivity is added to thecrystalline semiconductor films 706 and 708 to 710 at low concentrationby an ion doping method or an ion implantation method to form N-typeimpurity regions 711 and 713 to 715 and channel formation regions 780and 782 to 784. As the impurity element which imparts N-typeconductivity, an element belonging to Group 15 may be used and, forexample, phosphorus (P) or arsenic (As) is used.

Thereafter, a mask of resist is formed by a photolithography method andan impurity element which imparts P-type conductivity is added to thecrystalline semiconductor film 707 to form a P-type impurity region 712and a channel formation region 781. As the impurity element whichimparts P-type conductivity, for example, boron (B) is used.

Next, an insulating film is formed to cover the gate insulating film 705and the conductive films 716 to 725. The insulating film is formed byusing a single layer or a laminated layer of a film containing aninorganic material such as silicon, oxide of silicon, and/or nitride ofsilicon or a film containing an organic material such as an organicresin by a plasma CVD method, a sputtering method, or the like. Next,the insulating film is selectively etched by anisotropic etching, bywhich etching is performed mainly in a perpendicular direction, to forminsulating films (also referred to as sidewalls) 739 to 743 in contactwith side faces of the conductive films 716 to 725 (FIG. 9C). At thesame time as the manufacturing of the insulating films 739 to 743, thegate insulating film 705 is etched to form insulating films 734 to 738.The insulating films 739 to 743 are used as masks for doping whenforming source and drain regions later.

Subsequently, with the use of the mask of resist formed by aphotolithography method and the insulating films 739 to 743 as masks, animpurity element which imparts N-type conductivity is added to thecrystalline semiconductor films 706 and 708 to 710 to form first N-typeimpurity regions 727, 729, 731, and 733 serving as LDD (Lightly DopedDrain) regions and second N-type impurity regions 726, 728, 730, and732. The concentration of the impurity element contained in the firstN-type impurity regions 727, 729, 731, and 733 is lower than that in thesecond N-type impurity regions 726, 728, 730, and 732. Through the abovesteps, N-type thin film transistors 744 and 746 to 748 and a P-type thinfilm transistor 745 are completed.

Note that there is a technique using the sidewall insulating film as amask in order to form the LDD region. With the technique using thesidewall insulating film as a mask, a width of the LDD region can beeasily controlled, and the LDD region can be formed certainly.

Subsequently, a single layer or laminated layer of an insulating film isformed to cover the thin film transistors 744 to 748 (FIG. 10A). Theinsulating film covering the thin film transistors 744 to 748 is formedby an SOG method, a droplet discharge method, or the like with a singlelayer or a laminated layer of an inorganic material such as oxide ofsilicon and/or nitride of silicon, an organic material such aspolyimide, polyamide, benzocyclobutene, acrylic, epoxy, or siloxane, orthe like. A siloxane-based material corresponds to a material of whichskeleton is formed with a bond of silicon and oxygen and which includesat least hydrogen as a substituent, or a material of which skeleton isformed with a bond of silicon and oxygen and which includes at least oneof fluorine, an alkyl group, and aromatic hydrocarbon as a substituent.For example, in the case where the insulating film covering the thinfilm transistors 744 to 748 has a three-layer structure, a filmcontaining silicon oxide may be formed as a first insulating film 749, afilm containing a resin may be formed as a second insulating film 750,and a film containing silicon nitride may be formed as a thirdinsulating film 751.

Note that heat treatment for recovering crystallinity of thesemiconductor films, activating the impurity elements added to thesemiconductor films, or hydrogenating the semiconductor films, ispreferably performed before forming the insulating films 749 to 751 orafter forming one or a plurality of the insulating films 749 to 751. Theheat treatment is preferably performed by applying a thermal annealingmethod, a laser annealing method, an RTA method, or the like.

Next, the insulating films 749 to 751 are etched by a photolithographymethod to form contact holes which expose the second N-type impurityregions 726 and 728 to 732 and the P-type impurity region 712.Subsequently, a conductive film is formed to fill the contact holes. Theconductive film is patterned to form conductive films 752 to 761functioning as source and drain wires.

The conductive films 752 to 761 are formed by a CVD method, a sputteringmethod, or the like with a single layer or a laminated layer of anelement selected from aluminum (Al), tungsten (W), titanium (Ti),tantalum (Ta), molybdenum (Mo), nickel (Ni), platinum (Pt), copper (Cu),gold (Au), silver (Ag), manganese (Mn), neodymium (Nd), carbon (C), andsilicon (Si) or an alloy material or a compound material containing theelement as its main component. The alloy material containing aluminum asits main component corresponds to, for example, a material containingaluminum as its component and nickel or an alloy material containingaluminum as its main component, nickel, and either or both carbon andsilicon. The conductive films 752 to 761 may have, for example, alaminated structure of a barrier film, an aluminum silicon (Al—Si) film,and a barrier film or a laminated structure of a barrier film, analuminum silicon (Al—Si) film, a titanium nitride (TiN) film, and abarrier film. Note that the barrier film corresponds to a thin film oftitanium, nitride of titanium, molybdenum, or nitride of molybdenum.Aluminum and aluminum silicon have low resistance and are inexpensive,which are optimum for a material of the conductive films 752 to 761.When upper and lower barrier layers are provided, generation of ahillock of aluminum or aluminum silicon can be prevented. By forming thebarrier film of titanium that is an element having a high reducingproperty, even when a thin natural oxide film is formed on thecrystalline semiconductor film, the natural oxide film can be reduced,so that favorable contact with the crystalline semiconductor film can beformed.

Next, an insulating film 762 is formed to cover the conductive films 752to 761 (FIG. 10B). The insulating film 762 is formed with a single layeror a laminated layer of an inorganic material or an organic material byan SOG method, a droplet discharge method, or a printing method such asa screen printing method or a gravure printing method. In addition, theinsulating film 762 is preferably formed with a thickness of 0.75 μm to3 μm.

Subsequently, the insulating film 762 is etched by a photolithographymethod to form contact holes which expose the conductive films 757, 759,and 761. Then, a conductive film is formed to fill the contact holes.The conductive film is formed of a conductive material using a plasmaCVD method, a sputtering method, or the like. Next, the conductive filmis patterned to form conductive films 763 to 765. Note that each of theconductive films 763 and 764 serves as one of a pair of conductive filmsincluded in a storage element. Consequently, the conductive films 763 to765 are preferably formed with a single layer or a laminated layer oftitanium or an alloy material or a compound material containing titaniumas its main component. Titanium has low resistance, which leads to areduction in size of a storage element and achievement of higherintegration. In a photolithography step to form the conductive films 763to 765, wet etching processing is preferably performed so as not todamage the thin film transistors 744 to 748 therebelow, and hydrogenfluoride (HF) or ammonia peroxide is preferably used as an etchant.

Next, an insulating film 766 is formed to cover the conductive films 763to 765. The insulating film 766 is formed with a single layer or alaminated layer of an inorganic material or an organic material by anSOG method, a droplet discharge method, or the like. The insulating film762 is preferably formed with a thickness of 0.75 μm to 3 μm.Subsequently, the insulating film 766 is etched by a photolithographymethod to form contact holes 767 to 769 which expose the conductivefilms 763 to 765.

Next, a conductive film 786 functioning as an antenna is formed incontact with the conductive film 765 (FIG. 11A). The conductive film 786is formed of a conductive material by a CVD method, a sputtering method,a printing method, a droplet discharge method, or the like. Preferably,the conductive film 786 is formed with a single layer or a laminatedlayer of an element selected from aluminum (Al), titanium (Ti), silver(Ag), copper (Cu), and gold (Au) or an alloy material or a compoundmaterial containing the element as its main component. Specifically, theconductive film 786 is formed by using paste containing silver by ascreen printing method and then performing heat treatment at atemperature of 50° C. to 350° C. Alternatively, the conductive film 786is formed by forming an aluminum film by a sputtering method andpatterning the aluminum film. The aluminum film may be patterned by wetetching processing, and after the wet etching processing, heat treatmentmay be performed at a temperature of 200° C. to 300° C.

Next, an organic compound layer 787 functioning as a storage element isformed to be in contact with the conductive films 763 and 764 (FIG.11B). A material of which property or state changes by an electricaleffect, an optical effect, a thermal effect, or the like is used as amaterial for the storage element. For example, a material, of whichproperty or state changes by melting due to Joule heat, dielectricbreakdown, or the like to cause an upper electrode and a lower electrodeto short, may be used. Therefore, a thickness of a layer used for thestorage element (here, the organic compound layer) is preferably 5 nm to100 nm, more preferably, 10 nm to 60 μM.

Here, the organic compound layer 787 is formed by a droplet dischargemethod, a spin coating method, a vapor deposition method, or the like.Subsequently, a conductive film 771 is formed to be in contact with theorganic compound layer 787. The conductive film 771 is formed by asputtering method, a spin coating method, a droplet discharge method, avapor deposition method, or the like.

Through the above-mentioned steps, a storage element portion 789including a lamination body of the conductive film 763, the organiccompound layer 787, and the conductive film 771 and a storage elementportion 790 including a lamination body of the conductive film 764, theorganic compound layer 787, and the conductive film 771 are formed.

Note that a feature of the above manufacturing steps is to perform thestep of forming the organic compound layer 787 after the step of formingthe conductive film 786 functioning as the antenna since heat resistanceof the organic compound layer 787 is not high.

As an organic material used for the organic compound layer, for example,an aromatic amine-based compound (that is, a compound having a benzenering-nitrogen bond) such as4,4′-bis[N-(1-naphthyl)-N-phenyl-animo]-biphenyl (abbr.: α-NPD),4,4′-bis[N-(3-methylphenyl)-N-phenyl-amino]-biphenyl (abbr.: TPD),4,4′,4″-tris(N,N-diphenyl-amino)-triphenylamine (abbr.: TDATA),4,4′,4″-tris[N-(3-methylphenyl)-N-phenyl-amino]-triphenylamine (abbr.:MTDATA), and4,4′-bis{N-[4-(N,N-di-m-tolylamino)phenyl]-N-phenylamino}biphenyl(abbr.: DNTPD), polyvinyl carbazole (abbr.: PVK), a phthalocyaninecompound such as phthalocyanine (abbr.: H₂Pc), copper phthalocyanine(abbr.: CuPc), or vanadyl phthalocyanine (abbr.: VOPc), or the like canbe used. These materials have a high hole transporting property.

Besides, a material formed of a metal complex or the like having aquinoline skeleton or a benzoquinoline skeleton such astris(8-quinolinolato)aluminum (abbr.: Alq₃),tris(4-methyl-8-quinolinolato)aluminum (abbr.: Almq₃),bis(10-hydroxybenzo[h]-quinolinato)beryllium (abbr.: BeBq₂), Orbis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum (abbr.: BAlq),a material formed of a metal complex or the like having an oxazole-basedor thiazole-based ligand such asbis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbr.: Zn(BOX)₂), orbis[2-(2-hydroxyphenyl)benzothiazolato]zinc (abbr.: Zn(BTZ)₂), or thelike can be used. These materials have a high electron transportingproperty.

Other than the metal complexes, a compound or the like such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbr.: PBD),1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbr.:OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole(abbr.: TAZ),3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole(abbr.: p-EtTAZ), bathophenanthroline (abbr.: BPhen), bathocuproin(abbr.: BCP), or the like can be used.

The organic compound layer may have a single-layer structure or alaminated structure. In the case of a laminated structure, materials canbe selected from the aforementioned materials to form a laminatedstructure. Further, the aforementioned organic material and a lightemitting material may be laminated. As the light emitting material,4-dicyanomethylene-2-methyl-6-[2-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran(abbr.: DOT),4-dicyanomethylene-2-t-butyl-6-[2-(1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]-4H-pyran,periflanthene,2,5-dicyano-1,4-bis[(10-methoxy-1,1,7,7-tetramethyljulolidine-9-yl)ethenyl]benzene,N,N′-dimethylquinacridone (abbr.: DMQd), coumarin 6, coumarin 545T,tris(8-quinolinolato)aluminum (abbr.: Alq₃), 9,9′-bianthlyl,9,10-diphenylanthracene (abbr.: DPA), 9,10-bis(2-naphthyl)anthracene(abbr.: DNA), 2,5,8,11-tetra-t-buthylperylene (abbr.: TBP), or the likecan be used.

A layer in which the above light emitting material is dispersed may beused. In the layer in which the above light emitting material isdispersed, an anthracene derivative such as9,10-di(2-naphthyl)-2-tert-butylanthracene (abbr.: t-BuDNA), a carbazolederivative such as 4,4′-di(N-carbazolyl)biphenyl (abbr.: CBP), a metalcomplex such as bis[2-(2-hydroxyphenyl)pyridinato]zinc (abbr.: Znpp₂) Orbis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbr.: ZnBOX), or the likecan be used as a base material. In addition,tris(8-quinolinolato)aluminum (abbr.: Alq₃),9,10-bis(2-naphthyl)anthracene (abbr.: DNA),bis(2-methyl-8-quinolinolato)-4-phenylphenolato-aluminum (abbr.: BAlq),or the like can be used.

Such an organic material is changed its property by a thermal effect orthe like; therefore, a glass transition temperature (Tg) thereof ispreferably 50° C. to 300° C., more preferably, 80° C. to 120° C.

In addition, a material in which metal oxide is mixed with an organicmaterial or a light emitting material may be used. Note that thematerial in which metal oxide is mixed includes a state in which metaloxide is mixed or laminated with the above organic material or the abovelight emitting material. Specifically, it indicates a state which isformed by a co-evaporation method using plural evaporation sources. Sucha material can be referred to as an organic-inorganic compositematerial.

For example, in the case of mixing a substance having a high holetransporting property with metal oxide, it is preferable to use vanadiumoxide, molybdenum oxide, niobium oxide, rhenium oxide, tungsten oxide,ruthenium oxide, titanium oxide, chromium oxide, zirconium oxide,hafnium oxide, or tantalum oxide as the metal oxide.

In the case of mixing a substance having a high electron transportingproperty with metal oxide, it is preferable to use lithium oxide,calcium oxide, sodium oxide, potassium oxide, or magnesium oxide as themetal oxide.

A material of which property changes by an electrical effect, an opticaleffect, or a thermal effect may be used for the organic compound layer;therefore, for example, a conjugated high molecular compound doped witha compound (photoacid generator) which generates acid by absorbing lightcan also be used. As the conjugated high molecular compound,polyacetylenes, polyphenylene vinylenes, polythiophenes, polyanilines,polyphenylene ethinylenes, or the like can be used. As the photoacidgenerator, aryl sulfonium salt, aryl iodonium salt, o-nitrobenzyltosylate, aryl sulfonic acid p-nitrobenzyl ester, sulfonylacetophenones, Fe-arene complex PF6 salt, or the like can be used.

Note that the example of using an organic compound material for thestorage element portions 789 and 790 is described here, but theinvention is not limited thereto. For example, a phase change materialsuch as a material which changes reversibly between a crystalline stateand an amorphous state or a material which changes reversibly between afirst crystalline state and a second crystalline state can be used.Further, a material which changes only from an amorphous state to acrystalline state can be used.

The material which reversibly changes between a crystalline state and anamorphous state is a material containing a plurality of elementsselected from germanium (Ge), tellurium (Te), antimony (Sb), sulphur(S), tellurium oxide (TeOx), tin (Sn), gold (Au), gallium (Ga), selenium(Se), indium (In), thallium (Tl), cobalt (Co), and silver (Ag). Forexample, a material based on Ge—Te—Sb—S, Te—TeO₂—Ge—Sn, Te—Ge—Sn—Au,Ge—Te—Sn, Sn—Se—Te, Sb—Se—Te, Sb—Se, Ga—Se—Te, Ga—Se—Te—Ge, In—Se,In—Se—Tl—Co, Ge—Sb—Te, In—Se—Te, or Ag—In—Sb—Te may be used. Thematerial which reversibly changes between the first crystalline stateand the second crystalline state is a material containing a plurality ofelements selected from silver (Ag), zinc (Zn), copper (Cu), aluminum(Al), nickel (Ni), indium (In), antimony (Sb), selenium (Se), andtellurium (Te), for example, Te—TeO₂, Te—TeO₂—Pd, or Sb₂Se₃/Bi₂Te₃. Whenusing this material, a phase change is carried out between two differentcrystalline states. The material which changes only from an amorphousstate to a crystalline state is a material containing a plurality ofelements selected from tellurium (Te), tellurium oxide (TeO_(X)),antimony (Sb), selenium (Se), and bismuth (Bi), for example, Ag—Zn,Cu—Al—Ni, In—Sb, In—Sb—Se, or In—Sb—Te.

Next, an insulating film 772 functioning as a protective film is formedby an SOG method, a spin coating method, a droplet discharge method, aprinting method, or the like to cover the storage element portions 789and 790 and the conductive film 786 functioning as the antenna. Theinsulating film 772 is formed of a film containing carbon such as DLC(Diamond Like Carbon), a film containing silicon nitride, a filmcontaining silicon nitride oxide, or an organic material, preferably, anepoxy resin.

Then, the substrate 701 is thinned or removed as described in the aboveembodiment modes (FIG. 12A). Here, an example of removing the substrate701 by performing grinding treatment, polishing treatment, etching bychemical treatment, or the like on the substrate 701 to expose theinsulating film 702 as shown in FIGS. 4A to 4C is described. Here, thesubstrate 701 is thinned using a grinding means 795. Note that polishingtreatment, etching using chemical treatment, or the like may beperformed after thinning the substrate 701 by the grinding means 795.Thus, in the case of performing grinding treatment, polishing treatment,etching by chemical treatment, or the like on the substrate 701 untilthe insulating film 702 is exposed, the insulating film 702 can be usedas a stopper.

Alternatively, after thinning the substrate 701 so that a part thereofremains, an insulating film functioning as a protective film may beformed by performing surface treatment on the remaining substrate 701 asshown in FIG. 6B, or an insulating film functioning as a protective filmcan be formed as shown in FIGS. 5A to 5D by performing surface treatmentafter thinning the substrate 701 without forming the insulating film702.

Next, sealing treatment is performed using a first sheet material 791and a second sheet material 792 (FIG. 12B).

The first sheet material 791 and the second sheet material 792 used forsealing may be a film made of polypropylene, polyester, vinyl, polyvinylfluoride, polyvinyl chloride, or the like, paper of a fibrous material,or a laminated film of a base film (polyester, polyamide, an inorganicvapor-deposited film, paper, or the like) and an adhesive syntheticresin film (an acrylic-based synthetic resin, an epoxy-based syntheticresin, or the like). The film may be subjected to heat treatment andpressure treatment with an object to be treated. In performing heattreatment and pressure treatment, an adhesive layer provided on theuppermost surface of the film or a layer (not an adhesive layer)provided on the outermost layer is melted by heat treatment to beattached by applying pressure. An adhesive layer may be provided on thesurface of the first sheet material 791 and the second sheet material792, but it is not necessarily provided. The adhesive layer correspondsto a layer containing an adhesive such as a thermosetting resin, a UVcuring resin, an epoxy-based resin, or a resin additive. The sheetmaterial used for sealing is preferably coated with silica to preventmoisture or the like from entering the inside after sealing, and forexample, a sheet material in which an adhesive layer, a film ofpolyester or the like, and silica coat are laminated can be used.

As the first sheet material 791 and the second sheet material 792, afilm subjected to antistatic treatment for preventing static electricityor the like (hereinafter referred to as an antistatic film) may be usedas well. An antistatic film includes a film where an antistatic materialis dispersed in a resin, a film to which an antistatic material isattached, and the like. A film containing an antistatic material may bea film having one surface provided with an antistatic material, or afilm having the both surfaces provided with an antistatic material. In afilm having one surface provided with an antistatic material, a surfacecontaining an antistatic material may be attached to the inside oroutside of the film. Note that an antistatic material may be providedover the entire surface or a part of a film. An antistatic materialherein includes metal, oxide of indium and tin (ITO), and a surfactantsuch as a zwitterionic surfactant, a cationic surfactant, and a nonionicsurfactant. Instead, a resin material containing a cross-linkedcopolymer high molecular compound having a carboxyl group and aquaternary ammonium base in a side chain may be used as an antistaticmaterial. An antistatic film may be obtained by attaching, kneading, orapplying these materials to a film. When a semiconductor device issealed with an antistatic film, the semiconductor element can beprotected from external static electricity or the like when beinghandled as a product.

Note that in the case of not particularly requiring sealing treatment, asemiconductor device can be completed with the structure shown in FIG.12A. In the sealing treatment, sealing of either the substrate 701 orthe insulating film 772 may be performed selectively.

Note that this embodiment mode can be freely combined with the aboveembodiment mode. In other words, the material or the formation methoddescribed in the above embodiment mode can be used in combination alsoin this embodiment mode, and the material or the formation methoddescribed in this embodiment mode can be used in combination also in theabove embodiment mode.

Embodiment Mode 4

In this embodiment mode, applications of a semiconductor device whichcan exchange data without contact are explained with reference to FIGS.13A to 13C. The semiconductor device which can exchange data withoutcontact is also referred to as an RFID (Radio Frequency Identification)tag, an ID tag, an IC tag, an IC chip, an RF (Radio Frequency) tag, awireless tag, an electronic tag, or a wireless chip depending onapplication modes.

A semiconductor device 80 has the function of communicating data withoutcontact, and includes a high frequency circuit 81, a power supplycircuit 82, a reset circuit 83, a clock generation circuit 84, a datademodulation circuit 85, a data modulation circuit 86, a control circuit87 for controlling other circuits, a storage circuit 88, and an antenna89 (FIG. 13A). The high frequency circuit 81 is a circuit which receivesa signal from the antenna 89 and outputs a signal received by the datamodulation circuit 86 from the antenna 89. The power supply circuit 82is a circuit which generates a power supply potential from the receivedsignal. The reset circuit 83 is a circuit which generates a resetsignal. The clock generation circuit 84 is a circuit which generatesvarious clock signals based on the received signal input from theantenna 89. The data demodulation circuit 85 is a circuit whichdemodulates the received signal and outputs the signal to the controlcircuit 87. The data modulation circuit 86 is a circuit which modulatesa signal received from the control circuit 87. As the control circuit87, a code extraction circuit 91, a code determination circuit 92, a CRCdetermination circuit 93, and an output unit circuit 94 are provided forexample. Note that the code extraction circuit 91 is a circuit whichseparately extracts a plurality of codes included in an instructiontransmitted to the control circuit 87. The code determination circuit 92is a circuit which compares the extracted code and a code correspondingto a reference to determine the content of the instruction. The CRCcircuit is a circuit which detects the presence or absence of atransmission error or the like based on the determined code.

In addition, the number of storage circuits to be provided is notlimited to one, and may be plural. An SRAM, a flash memory, a ROM, anFeRAM, or the like, or a circuit using the organic compound layerdescribed in the above embodiment mode in a storage element portion canbe used.

Next, an example of operation of a semiconductor device which cancommunicate data without contact of the present invention is explained.First, a radio signal is received by the antenna 89. The radio signal istransmitted to the power supply circuit 82 via the high frequencycircuit 81, and a high power supply potential (hereinafter referred toas VDD) is generated. The VDD is supplied to each circuit included inthe semiconductor device 80. In addition, a signal transmitted to thedata demodulation circuit 85 via the high frequency circuit 81 isdemodulated (hereinafter, a demodulated signal). Further, a signaltransmitted through the reset circuit 83 and the clock generationcircuit 84 via the high frequency circuit 81 and the demodulated circuit85 are transmitted to the control circuit 87. The signal transmitted tothe control circuit 87 is analyzed by the code extraction circuit 91,the code determination circuit 92, the CRC assessment circuit 93, andthe like. Then, in accordance with the analyzed signal, information ofthe semiconductor device stored in the storage circuit 88 is output. Theoutput information of the semiconductor device is encoded through theoutput unit circuit 94. Furthermore, the encoded information of thesemiconductor device 80 is transmitted by the antenna 89 as a radiosignal through the data modulation circuit 86. Note that a low powersupply potential (hereinafter, VSS) is common among a plurality ofcircuits included in the semiconductor device 80, and VSS can be set toGND.

Thus, data of the semiconductor device can be read by transmitting asignal from a reader/writer to the semiconductor device 80 and receivingthe signal transmitted from the semiconductor device 80 by thereader/writer.

In addition, the semiconductor device 80 may supply a power supplyvoltage to each circuit by an electromagnetic wave without a powersource (battery) mounted, or by an electromagnetic wave and a powersource (battery) with the power source (battery) mounted.

Since a semiconductor device which can be bent can be manufactured byusing the structure described in the above embodiment modes, thesemiconductor device can be provided over an object having a curvedsurface by attachment.

Subsequently, an example of an application of a semiconductor devicewhich can exchange data without contact is explained. A side face of aportable terminal including a display portion 3210 is provided with areader/writer 3200, and a side face of an article 3220 is provided witha semiconductor device 3230 (FIG. 13B). When the reader/writer 3200 isheld over the semiconductor device 3230 included in the article 3220,information on the article 3220 such as a raw material, the place oforigin, an inspection result in each production process, the history ofdistribution, or an explanation of the article is displayed on thedisplay portion 3210. Further, when a product 3260 is transported by aconveyor belt, the product 3260 can be inspected using a reader/writer3240 and a semiconductor device 3250 provided over the product 3260(FIG. 13C). Thus, by utilizing the semiconductor device for a system,information can be acquired easily, and improvement in functionality andadded value of the system can be achieved. As described in the aboveembodiment modes, a transistor or the like included in a semiconductordevice can be prevented from being damaged even when the semiconductordevice is attached to an object having a curved surface, and a reliablesemiconductor device can be provided.

In addition, as a signal transmission method in the above-describedsemiconductor device which can exchange data without contact, anelectromagnetic coupling method, an electromagnetic induction method, amicrowave method, or the like can be used. The transmission system maybe appropriately selected by a practitioner in consideration of anintended use, and an optimum antenna may be provided in accordance withthe transmission method.

In the case of employing, for example, an electromagnetic couplingmethod or an electromagnetic induction method (for example, a 13.56 MHzband) as the signal transmission method in the semiconductor device,electromagnetic induction caused by a change in magnetic field density.Therefore, the conductive film serving as the antenna is formed in anannular shape (for example, a loop antenna) or a spiral shape (forexample, a spiral antenna).

In the case of employing, for example, a microwave method (for example,a UHF band (860 to 960 MHz band), a 2.45 GHz band, or the like) as thesignal transmission method in the semiconductor device, the shape suchas a length of the conductive film serving as the antenna may beappropriately set in consideration of a wavelength of an electromagneticwave used for signal transmission. For example, the conductive filmserving the an antenna can be formed in a linear shape (for example, adipole antenna), a flat shape (for example, a patch antenna), or thelike. The shape of the conductive film serving as the antenna is notlimited to a linear shape, and the conductive film serving as theantenna may be provided in a curved-line shape, a meander shape, or acombination thereof, in consideration of a wavelength of anelectromagnetic wave.

The conductive film functioning as the antenna is formed of a conductivematerial by a CVD method, a sputtering method, a printing method such asscreen printing or gravure printing, a droplet discharge method, adispenser method, a plating method, or the like. The conductive film isformed with a single-layer structure or a laminated structure of anelement selected from aluminum (Al), titanium (Ti), silver (Ag), copper(Cu), gold (Au), platinum (Pt), nickel (Ni), palladium (Pd), tantalum(Ta), and molybdenum (Mo) or an alloy material or a compound materialcontaining the element as its main component.

In the case of forming a conductive film functioning as an antenna byusing, for example, a screen printing method, the conductive film can beprovided by selectively printing conductive paste in which conductiveparticles each having a grain size of several nm to several tens of μmare dissolved or dispersed in an organic resin. As the conductiveparticle, a fine particle or a dispersive nanoparticle of metal of oneor more of silver (Ag), gold (Au), copper (Cu), nickel (Ni), platinum(Pt), palladium (Pd), tantalum (Ta), molybdenum (Mo), and titanium (Ti)or silver halide can be used. In addition, as the organic resin includedin the conductive paste, one or a plurality of organic resins eachfunctioning as a binder, a solvent, a dispersant, or a coating of themetal particle can be used. Typically, an organic resin such as an epoxyresin or a silicon resin can be used. When forming a conductive film,baking is preferably performed after the conductive paste is applied.For example, in the case of using fine particles (of which grain size is1 nm to 100 nm) containing silver as its main component as a material ofthe conductive paste, a conductive film can be obtained by curing theconductive paste by baking at a temperature of 150° C. to 300° C.Alternatively, fine particles containing solder or lead-free solder asits main component may be used; in this case, it is preferable to use afine particle having a grain size of 20 μm. Solder or lead-free solderhas an advantage such as low cost.

Besides the above-mentioned material, ceramic, ferrite, or the like maybe applied to an antenna. Furthermore, a material of which dielectricconstant and magnetic permeability are negative in a microwave band(metamaterial) can be applied to an antenna.

In the case of applying an electromagnetic coupling method or anelectromagnetic induction method, and providing a semiconductor deviceincluding an antenna in contact with metal, a magnetic material havingmagnetic permeability is preferably provided between the semiconductordevice and metal. In the case of providing a semiconductor deviceincluding an antenna in contact with metal, an eddy current flows inmetal accompanying change in magnetic field, and a demagnetizing fieldgenerated by the eddy current impairs a change in magnetic field anddecreases a communication distance. Therefore, eddy current of metal anda decrease in communication range can be suppressed by providing amaterial having magnetic permeability between the semiconductor deviceand metal. Note that ferrite or a metal thin film having high magneticpermeability and little loss of high frequency wave can be used as themagnetic material.

In the case of providing an antenna, a semiconductor element such as atransistor and a conductive film functioning as an antenna may bedirectly formed over one substrate, or a semiconductor element and aconductive film functioning as an antenna may be provided over separatesubstrates and then attached to be electrically connected to each other.

Note that an applicable range of the flexible semiconductor device iswide in addition to the above, and the flexible semiconductor device canbe applied to any product as long as it clarifies information such asthe history of an object without contact and is useful for production,management, or the like. For example, the semiconductor device can bemounted on paper money, coins, securities, certificates, bearer bonds,packing containers, books, recording media, personal belongings,vehicles, food, clothing, health products, commodities, medicine,electronic devices, and the like. Examples of them are explained withreference to FIGS. 14A to 14H.

The paper money and coins are money distributed to the market andinclude one valid in a certain area (cash voucher), memorial coins, andthe like. The securities refer to checks, certificates, promissorynotes, and the like (FIG. 14A). The certificates refer to driver'slicenses, certificates of residence, and the like (FIG. 14B). The bearerbonds refer to stamps, rice coupons, various gift certificates, and thelike (FIG. 14C). The packing containers refer to wrapping paper for foodcontainers and the like, plastic bottles, and the like (FIG. 14D). Thebooks refer to hardbacks, paperbacks, and the like (FIG. 14E). Therecording media refer to DVD software, video tapes, and the like (FIG.14F). The vehicles refer to wheeled vehicles such as bicycles, ships,and the like (FIG. 14G). The personal belongings refer to bags, glasses,and the like (FIG. 14H). The food refers to food articles, drink, andthe like. The clothing refers to clothes, footwear, and the like. Thehealth products refer to medical instruments, health instruments, andthe like. The commodities refer to furniture, lighting equipment, andthe like. The medicine refers to medical products, pesticides, and thelike. The electronic devices refer to liquid crystal display devices, ELdisplay devices, television devices (TV sets and flat-screen TV sets),cellular phones, and the like.

Forgery can be prevented by providing the paper money, the coins, thesecurities, the certificates, the bearer bonds, or the like with thesemiconductor device. The efficiency of an inspection system, a systemused in a rental shop, or the like can be improved by providing thepacking containers, the books, the recording media, the personalbelongings, the food, the commodities, the electronic devices, or thelike with the semiconductor device. Forgery or theft can be prevented byproviding the vehicles, the health products, the medicine, or the likewith the semiconductor device; further, in the case of the medicine,medicine can be prevented from being taken mistakenly. The semiconductordevice can be mounted on the foregoing article by being attached to thesurface or being embedded therein. For example, in the case of a book,the semiconductor device may be embedded in a piece of paper; in thecase of a package made from an organic resin, the semiconductor devicemay be embedded in the organic resin. By using a flexible semiconductordevice having the structure described in the above embodiment mode,breakage or the like of an element included in the semiconductor devicecan be prevented even when the semiconductor device is mounted on paperor the like.

As described above, the efficiency of an inspection system, a systemused in a rental shop, or the like can be improved by providing thepacking containers, the recording media, the personal belonging, thefood, the clothing, the commodities, the electronic devices, or the likewith the semiconductor device. In addition, by providing the vehicleswith the semiconductor device, forgery or theft can be prevented.Further, by implanting the semiconductor device in a creature such as ananimal, an individual creature can be easily identified. For example, byimplanting the semiconductor device with a sensor in a creature such aslivestock, its health condition such as a current body temperature aswell as its birth year, sex, breed, or the like can be easily managed.

Note that this embodiment mode can be freely combined with the aboveembodiment mode. In other words, the material or the formation methoddescribed in the above embodiment mode can be used in combination alsoin this embodiment mode, and the material or the formation methoddescribed in this embodiment mode can be used in combination also in theabove embodiment mode.

Embodiment Mode 5

In this embodiment mode, a structure of a semiconductor device of thepresent invention, which is different from those in the above embodimentmodes, is explained with reference to drawings. Specifically, an exampleof a semiconductor device having a pixel portion is explained.

First, the case of providing a light emitting element in a pixel portionis explained with reference to FIGS. 15A and 15B. Note that FIG. 15A isa top view showing an example of a semiconductor device of the presentinvention, and FIG. 15B is a cross-sectional view of FIG. 15A takenalong lines a-b and c-d.

As shown in FIG. 15A, a semiconductor device described in thisembodiment mode includes a scan line driver circuit 502, a signal linedriver circuit 503, and a pixel portion 504 which are provided over asubstrate 501. In addition, an opposite substrate 506 is provided tosandwich the pixel portion 504 with the substrate 501. The scan linedriver circuit 502, the signal line driver circuit 503, and the pixelportion 504 can be provided by forming thin film transistors each havingany of the structures described in the above embodiment mode. Thesubstrate 501 and the opposite substrate 506 are attached to each otherwith a sealant 505. The scan line driver circuit 502 and the signal linedriver circuit 503 receive a video signal, a clock signal, a startsignal, a reset signal, or the like from an FPC (Flexible PrintedCircuit) 507 serving as an external input terminal. Note that only theFPC is shown here; however, the FPC may be provided with a printedwiring board (PWB).

FIG. 15B is a cross-sectional view of FIG. 15A taken along lines a-b andc-d. Here, thin film transistors included in the signal line drivercircuit 503 and the pixel portion 504 are provided over the substrate501 with an insulating film 520 functioning as a protective filminterposed therebetween. A CMOS circuit that is a combination of anN-type thin film transistor 510 a and a P-type thin film transistor 510b having any of the structure described in the above embodiment mode isformed as the signal line driver circuit 503. The driver circuit such asthe scan line driver circuit 502 or the signal line driver circuit 503may be formed using a CMOS circuit, a PMOS circuit, or an NMOS circuit.A driver integration type in which a driver circuit such as the scanline deriver circuit 502 and the signal line driver circuit 503 areformed over the substrate 501 is described in this embodiment mode, butit is not necessarily required and a driver circuit can be formedoutside the substrate 501. In addition, an insulating film 526functioning as a protective film is provided on the surface of theopposite substrate 506. Note that the substrate 501 may have any of thestructures described in the above embodiment modes. Here, after formingthe insulating film 520 functioning as a protective film by performingsurface treatment on one side of the substrate, a semiconductor elementis provided over the insulating film 520, and the substrate is thinnedfrom the other side, thereby obtaining the substrate 501. Further, theopposite substrate 506 is provided with an insulating film 526functioning as a protective film by performing surface treatment afterthinning the substrate.

The pixel portion 504 is formed with a plurality of pixels eachincluding a light emitting element 516 and a thin film transistor 511for driving the light emitting element 516. A thin film transistorhaving any of the structures described in the above embodiment modes canbe applied to the thin film transistor 511. Here, a first electrode 513is provided so as to be connected to a conductive film 512 connected toa source or drain region of the thin film transistor 511, and aninsulating film 509 is formed to cover an end portion of the firstelectrode 513. The insulating film 509 functions as a partition in aplurality of pixels.

As the insulating film 509, a positive type photosensitive acrylic resinfilm is used here. The insulating film 509 is formed to have a curvedsurface at an upper end portion or a lower end portion thereof in orderto make the coverage favorable. For example, in the case of usingpositive type photosensitive acrylic as a material of the insulatingfilm 509, the insulating film 509 is preferably formed to have a curvedsurface with a curvature radius (0.2 μM to 3 μm) only at an upper endportion. Either a negative type which becomes insoluble in an etchant bylight irradiation or a positive type which becomes soluble in an etchantby light irradiation can be used as the insulating film 509.Alternatively, the insulating film 509 can be provided with a singlelayer or a laminated structure of an organic material such as epoxy,polyimide, polyamide, polyvinylphenol, or benzocyclobutene or a siloxaneresin. As described in the above embodiment mode, the surface of theinsulating film 509 can be modified to obtain a dense film by performingplasma treatment on the insulating film 509 and oxidizing or nitridingthe insulating film 509. By modifying the surface of the insulating film509, intensity of the insulating film 509 can be improved, and physicaldamage such as crack generation at the time of forming an opening or thelike or film reduction at the time of etching can be reduced.Furthermore, by modifying the surface of the insulating film 509,interfacial quality such as adhesion with a light emitting layer 514 tobe provided over the insulating film 509 is improved.

In addition, in the semiconductor device shown in FIGS. 15A and 15B, alight emitting layer 514 is formed over the first electrode 513, and asecond electrode 515 is formed over the light emitting layer 514. Alight emitting element 516 is provided with a laminated structure of thefirst electrode 513, the light emitting layer 514, and the secondelectrode 515.

One of the first electrode 513 and the second electrode 515 is used asan anode, and the other is used as a cathode.

A material having a high work function is preferably used for an anode.For example, a single-layer film such as an ITO film, an indium tinoxide film containing silicon, a transparent conductive film formed by asputtering method using a target in which indium oxide is mixed withzinc oxide (ZnO) of 2 wt % to 20 wt %, a zinc oxide (ZnO) film, atitanium nitride film, a chromium film, a tungsten film, a Zn film, or aPt film; a laminated layer of a film containing titanium nitride as itsmain component and a film containing aluminum as its main component; athree-layer structure of a titanium nitride film, a film containingaluminum as its main component, and another titanium nitride film; orthe like. When a laminated structure is employed, an electrode can havelow resistance as a wire and form a favorable ohmic contact. Further,the electrode can function as an anode.

A material having a low work function (Al, Ag, Li, Ca, or an alloythereof such as MgAg, Men, AILi, CaF₂, or calcium nitride) is preferablyused for a cathode. In the case where an electrode used as a cathode ismade to transmit light, a laminated layer of a metal thin film with asmall thickness and a transparent conductive film (of ITO, indium tinoxide containing silicon, a transparent conductive film formed by asputtering method using a target in which indium oxide is mixed withzinc oxide (ZnO) of 2 wt % to 20 wt %, zinc oxide (ZnO), or the like) ispreferably used as the electrode.

Here, the first electrode 513 is formed using ITO which has a lighttransmitting property as an anode, and light is extracted from thesubstrate 501 side. Note that light may be extracted form the oppositesubstrate 506 side by using a material having a light transmittingproperty for the second electrode 515, or light can be extracted fromboth the substrate 501 side and the opposite substrate 506 side byforming the first electrode 513 and the second electrode 515 with amaterial having a light transmitting property (this structure isreferred to as dual emission).

The light emitting layer 514 can be formed with a single layer or alaminated structure of a low molecular material, an intermediatemolecular material (including an oligomer and a dendrimer), or a highmolecular material (also referred to as a polymer) by various methodssuch as a vapor deposition method using an evaporation mask, an ink-jetmethod, and a spin coating method.

By attaching the substrate 501 to the opposite substrate 506 with thesealant 505, the light emitting element 516 according to the presentinvention is provided in a space 508 surrounded by the substrate 501,the opposite substrate 506, and the sealant 505. Note that there arecases where the space 508 is filled with the sealant 505 as well as aninert gas (nitrogen, argon, or the like).

Note that an epoxy-based resin is preferably used as the sealant 505.The material preferably allows as little moisture and oxygen as possibleto penetrate. As a material of the opposite substrate 506, a plasticsubstrate formed of PRP (Fiberglass-Reinforced Plastics), PVF (polyvinylfluoride), Myler, polyester, acrylic, or the like can be used besides aglass substrate or a quartz substrate. The opposite substrate 506 can bethinned similarly as described in the above embodiment mode. Aprotective film may be formed by performing surface treatment afterthinning; here, an example of providing the insulating film 526functioning as a protective film by performing surface treatment on theopposite substrate 506 is described. Alternatively, the insulating film526 functioning as a protective film can be provided by performing thesurface treatment described in the above embodiment mode afterpreviously providing a plastic substrate.

Note that the semiconductor device including a pixel portion is notlimited to the above-described structure using a light emitting elementin a pixel portion, and it also includes a semiconductor device usingliquid crystal in a pixel portion. The semiconductor device using liquidcrystal in a pixel portion is shown in FIG. 16.

FIG. 16 shows an example of a semiconductor device having liquid crystalin a pixel portion. Liquid crystal 522 is provided between anorientation film 521 provided to cover the conductive film 512 and thefirst electrode 513 and an orientation film 523 provided over theopposite substrate 506. In addition, a second electrode 524 is providedover the opposite substrate 506. An image is displayed by controllinglight transmittance by controlling a voltage applied to liquid crystalprovided between the first electrode 513 and the second electrode 524.Further, a spherical spacer 525 is provided in the liquid crystal 522 tocontrol the distance (cell gap) between the first electrode 513 and thesecond electrode 524. Note that any of the structures described in thisembodiment mode can be applied to the thin film transistors 510 a, 510b, and 511.

As described above, in the semiconductor device described in thisembodiment mode, the pixel portion may be provided with a light emittingelement or liquid crystal.

Next, applications of a semiconductor device including the above pixelportion are explained with reference to drawings.

Application examples of a semiconductor device including the above pixelportion can be given as follows: a camera such as a video camera or adigital camera, a goggle type display (head mounted display), anavigation system, an audio reproducing device (car audio, an audiocomponent, or the like), a computer, a game machine, a portableinformation terminal (a mobile computer, a cellular phone, a portablegame machine, an electronic book, or the like), an image reproducingdevice including a recording medium reading portion (specifically, adevice capable of processing data in a recording medium such as adigital versatile disc (DVD) and having a display which can display theimage of the data), and the like. Practical examples of these electronicdevices are described below.

FIG. 17A shows a TV receiver, which includes a chassis 2001, a support2002, a display portion 2003, speaker portions 2004, a video inputterminal 2005, or the like. The TV receiver can be manufactured byapplying the structure described in Embodiment Mode 1 or 2 to asemiconductor device having a thin film transistor provided in thedisplay portion 2003, a driver circuit, or the like.

FIG. 17B shows a digital camera, which includes a main body 2101, adisplay portion 2102, an image receiving portion 2103, an operation key2104, an external connection port 2105, a shutter 2106, or the like. Thedigital camera can be manufactured by applying the structure ormanufacturing method described in the above embodiment mode to asemiconductor device having a thin film transistor provided in thedisplay portion 2102, a driver circuit, or the like.

FIG. 17C shows a computer, which includes a main body 2201, a chassis2202, a display portion 2203, a keyboard 2204, an external connectionport 2205, a pointing mouse 2206, or the like. The computer can bemanufactured by applying the structure or manufacturing method describedin the above embodiment mode to a semiconductor device having a thinfilm transistor provided in the display portion 2203, a driver circuit,or the like.

FIG. 17D shows a mobile computer, which includes a main body 2301, adisplay portion 2302, a switch 2303, an operation key 2304, an infraredport 2305, or the like. The mobile computer can be manufactured byapplying the structure or manufacturing method described in the aboveembodiment mode to a semiconductor device having a thin film transistorprovided in the display portion 2302, a driver circuit, or the like.

FIG. 17E shows a portable image reproducing device having a recordingmedium reading portion (a DVD reproducing device or the like), whichincludes a main body 2401, a chassis 2402, a display portion A 2403, adisplay portion B 2404, a recording medium (DVD or the like) readingportion 2405, an operation key 2406, a speaker portion 2407, or thelike. The display portion A 2403 mainly displays image information, andthe display portion B 2404 mainly displays textual information. Theimage reproducing device can be manufactured by applying the structureor manufacturing method described in the above embodiment mode to asemiconductor device having a thin film transistor provided in thedisplay portion A 2403, the display portion B 2404, a driver circuit, orthe like. Note that the image reproducing device having a recordingmedium reading portion includes a game machine and the like.

FIG. 17F shows a video camera, which includes a main body 2601, adisplay portion 2602, a chassis 2603, an external connection port 2604,a remote control receiving portion 2605, an image receiving portion2606, a battery 2607, an audio input portion 2608, an operation key2609, an eye piece portion 2610, or the like. The video camera can bemanufactured by applying the structure or manufacturing method describedin the above embodiment mode to a semiconductor device having a thinfilm transistor provided in the display portion 2602, a driver circuit,or the like.

FIG. 17G shows a cellular phone, which includes a main body 2701, achassis 2702, a display portion 2703, an audio input portion 2704, anaudio output portion 2705, an operation key 2706, an external connectionport 2707, an antenna 2708, or the like. The cellular phone can bemanufactured by applying the structure or manufacturing method describedin the above embodiment mode to a semiconductor device having a thinfilm transistor provided in the display portion 2703, a driver circuit,or the like.

The semiconductor device of the present invention can be made flexibleby thinning a substrate. Hereinafter, a specific example of a flexiblesemiconductor device having a pixel portion is explained with referenceto drawings.

FIG. 18A shows a display, which includes a main body 4101, a support4102, a display portion 4103, and the like. The display portion 4103 isformed using a flexible substrate, which can realize a lightweight andthin display. In addition, the display portion 4103 can be curved, andcan be detached from the support 4102 and the display can be mountedalong a curved wall. Thus, the flexible display can be provided over acurved portion as well as a flat surface; therefore, it can be used forvarious applications. A flexible display can be manufactured by usingthe flexible semiconductor device described in this embodiment mode orthe above embodiment mode for the display portion 4103, a circuit, orthe like.

FIG. 18B shows a display that can be wound, which includes a main body4201, a display portion 4202, and the like. Since the main body 4201 andthe display portion 4202 are formed using a flexible substrate, thedisplay can be carried in a bent or wound state. Therefore, even in thecase where the display is large-size, the display can be carried in abag in a bent or wound state. A flexible, lightweight, and thinlarge-sized display can be manufactured by using the flexiblesemiconductor device described in this embodiment mode or the aboveembodiment mode for the display portion 4202, a circuit, or the like.

FIG. 18C shows a sheet-type computer, which includes a main body 4401, adisplay portion 4402, a keyboard 4403, a touch pad 4404, an externalconnection port 4405, a power plug 4406, and the like. The displayportion 4402 is formed using a flexible substrate, which can realize alightweight and thin computer. In addition, the display portion 4402 canbe wound and stored in the main body if a portion of the main body 4401is provided with a storage space. In addition, by also forming the keyboard 4403 to be flexible, the keyboard 4403 can be wound and stored inthe storage space of the main body 4401 in a similar manner to thedisplay portion 4402, which is convenient for carrying around. Thecomputer can be stored without taking a place by bending when it is notused. A flexible, lightweight, and thin computer can be manufactured byusing the flexible semiconductor device described in this embodimentmode or the above embodiment mode for the display portion 4402, acircuit, or the like.

FIG. 18D shows a display device having a 20-inch to 80-inch large-sizeddisplay portion, which includes a main body 4300, a keyboard 4301 thatis an operation portion, a display portion 4302, a speaker 4303, and thelike. The display portion 4302 is formed using a flexible substrate, andthe main body 4300 can be carried in a bent or wound state with thekeyboard 4301 detached. In addition, the connection between the keyboard4301 and the display portion 4302 can be performed without wires. Forexample, the main body 4300 can be mounted along a curved wall and canbe operated with the key board 4301 without wires. In this case, aflexible, lightweight, and thin large-sized display device can bemanufactured by using the flexible semiconductor device described inthis embodiment mode or the above embodiment mode for the displayportion 4302, a circuit, or the like.

FIG. 18E shows an electronic book, which includes a main body 4501, adisplay portion 4502, an operation key 4503, and the like. In addition,a modem may be incorporated in the main body 4501. The display portion4502 is formed using a flexible substrate and can be bent or wound.Therefore, the electronic book can also be carried without taking aplace. Further, the display portion 4502 can display a moving image aswell as a still image such as a character. A flexible, lightweight, andthin electronic book can be manufactured by using the flexiblesemiconductor device described in this embodiment mode or the aboveembodiment mode for the display portion 4502, a circuit, or the like.

FIG. 18F shows an IC card, which includes a main body 4601, a displayportion 4602, a connection terminal 4603, and the like. Since thedisplay portion 4602 is formed to be a lightweight and thin sheet typeusing a flexible substrate, it can be formed over a card surface byattachment. When the IC card can receive data without contact,information obtained from outside can be displayed on the displayportion 4602. A flexible, lightweight, and thin IC card can bemanufactured by using the flexible semiconductor device described inthis embodiment mode or the above embodiment mode for the displayportion 4602, a circuit, or the like.

As described above, an applicable range of the semiconductor device ofthe invention is so wide that the semiconductor device of the inventioncan be applied to electronic devices of various fields. Note that thisembodiment mode can be freely combined with the above embodiment mode.

This application is based on Japanese Patent Application serial no.2005-192420 filed in Japan Patent Office on Jun. 30, 2005, the contentsof which are hereby incorporated by reference.

1. A method for manufacturing a semiconductor device comprising the steps of: performing plasma treatment on a glass substrate using a microwave in a nitrogen atmosphere; forming an element group over the glass substrate after performing the plasma treatment; and thinning the glass substrate after forming the element group.
 2. The method for manufacturing the semiconductor device according to claim 1, wherein the glass substrate is thinned by performing either or both grinding treatment and polishing treatment.
 3. The method for manufacturing the semiconductor device according to claim 1, wherein the nitrogen atmosphere is an atmosphere containing nitrogen and a noble gas, an atmosphere containing NH₃ and a noble gas, an atmosphere containing NO₂ and a noble gas, or an atmosphere containing N₂O and a noble gas.
 4. The method for manufacturing the semiconductor device according to claim 1, wherein the plasma treatment is performed under a condition that an electron density is in the range of 1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³ and an electron temperature is in the range of 0.5 eV to 1.5 eV.
 5. A method for manufacturing a semiconductor device comprising the steps of: performing plasma treatment on a glass substrate using a microwave in a nitrogen atmosphere; forming an element group over the glass substrate after performing the plasma treatment; thinning the glass substrate to form a thinned glass substrate; and performing sealing with a flexible film so as to cover the thinned glass substrate and the element group.
 6. The method for manufacturing the semiconductor device according to claim 5, wherein the glass substrate is thinned by performing either or both grinding treatment and polishing treatment.
 7. The method for manufacturing the semiconductor device according to claim 5, wherein the nitrogen atmosphere is an atmosphere containing nitrogen and a noble gas, an atmosphere containing NH₃ and a noble gas, an atmosphere containing NO₂ and a noble gas, or an atmosphere containing N₂O and a noble gas.
 8. The method for manufacturing the semiconductor device according to claim 5, wherein the plasma treatment is performed under a condition that an electron density is in the range of 1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³ and an electron temperature is in the range of 0.5 eV to 1.5 eV.
 9. A method for manufacturing a semiconductor device comprising the steps of: performing plasma treatment on a substrate using a microwave in a nitrogen atmosphere; forming an element group over the substrate after performing the plasma treatment; thinning the substrate to form a thinned substrate; and performing chemical treatment to the thinned substrate to remove the thinned substrate.
 10. The method for manufacturing the semiconductor device according to claim 9, wherein the substrate is thinned by performing either or both grinding treatment and polishing treatment.
 11. The method for manufacturing the semiconductor device according to claim 9, wherein the nitrogen atmosphere is an atmosphere containing nitrogen and a noble gas, an atmosphere containing NH₃ and a noble gas, an atmosphere containing NO₂ and a noble gas, or an atmosphere containing N₂O and a noble gas.
 12. The method for manufacturing the semiconductor device according to claim 9, wherein the plasma treatment is performed under a condition that an electron density is in the range of 1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³ and an electron temperature is in the range of 0.5 eV to 1.5 eV.
 13. A method for manufacturing a semiconductor device comprising the steps of: performing plasma treatment on a substrate using a microwave in a nitrogen atmosphere; forming an element group over the substrate after performing the plasma treatment; thinning the substrate to form a thinned substrate; performing chemical treatment to the thinned substrate to remove the thinned substrate; and performing sealing with a flexible film so as to cover the element group.
 14. The method for manufacturing the semiconductor device according to claim 13, wherein the substrate is thinned by performing either or both grinding treatment and polishing treatment.
 15. The method for manufacturing the semiconductor device according to claim 13, wherein the nitrogen atmosphere is an atmosphere containing nitrogen and a noble gas, an atmosphere containing NH₃ and a noble gas, an atmosphere containing NO₂ and a noble gas, or an atmosphere containing N₂O and a noble gas.
 16. The method for manufacturing the semiconductor device according to claim 13, wherein the plasma treatment is performed under a condition that an electron density is in the range of 1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³ and an electron temperature is in the range of 0.5 eV to 1.5 eV.
 17. A method for manufacturing a semiconductor device comprising the steps of: performing plasma treatment on a substrate using a microwave in a nitrogen atmosphere; forming an element group over the substrate after performing the plasma treatment; and removing the substrate.
 18. The method for manufacturing the semiconductor device according to claim 17, wherein the substrate is removed by performing at least chemical treatment.
 19. The method for manufacturing the semiconductor device according to claim 17, wherein sealing is performed with a flexible film so as to cover the element group.
 20. The method for manufacturing the semiconductor device according to claim 17, wherein the nitrogen atmosphere is an atmosphere containing nitrogen and a noble gas, an atmosphere containing NH₃ and a noble gas, an atmosphere containing NO₂ and a noble gas, or an atmosphere containing N₂O and a noble gas.
 21. The method for manufacturing the semiconductor device according to claim 17, wherein the plasma treatment is performed under a condition that an electron density is in the range of 1×10¹¹ cm⁻³ to 1×10¹³ cm⁻³ and an electron temperature is in the range of 0.5 eV to 1.5 eV. 